Date read: 29-09-2022

Author: Aaron Spitz

How strongly I recommend it: 5/10

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Read more summaries

Everything you need to know about the male sex organ. Contains a lot of important information for anyone who has a penis. However, the book is written for “skimmers”. As a result, each chapter tends to repeat information from previous chapters. This made the book longer than necessary.

My notes


  • The veins that drain the blood out of the penis travel through the walls of the shaft cylinders, but as the cylinders expand under pressure, they pinch the veins shut, trapping the blood in the erect penis. The pressure inside the shaft rises higher than the blood pressure in the rest of the body, and additional blood can no longer be pumped into the penis.
  • Adrenaline prepares your body to survive danger. It makes the blood vessels to your muscles, liver, heart, and brain open up more to preserve these vital structures but clamps down on the smaller blood vessels in your less vital parts like fingertips, toes, and your penis.
  • An adrenaline rush can occur from your perception of real danger, from imagined danger, or even just from stress or anxiety. Your penis will not know the difference.

Ejaculation and orgasm

  • The little head (between your legs) and the big head (on your shoulders) both generate key signals that jump from nerve to nerve, zipping along to meet in a specialized part of your lower spine known as the “spinal ejaculation center.
  • From the penis, sensations of touch, pressure, and vibration enter their “launch sequence”; this is compared with sequences generated by the rest of the sense organs sending information to the big head.
  • They release hormones into the bloodstream that trigger the testicles to produce both sperm and testosterone. Testosterone circulates back to the brain, where it stokes the fire of sexual desire.
  • This deep-brain center also releases a hormone called oxytocin. It reinforces positive feelings in the brain and it directly triggers the spinal ejaculation center. A third trigger from this brain center is dopamine. The more dopamine, the faster you recover after an ejaculation and can go for seconds or thirds.
  • However, there is a point of no return that scientists call “ejaculatory inevitability.” At this point the sympathetic nerves running down the spine into the pelvis, take over and release adrenaline which is what actually “cleans the pipes.”
  • At the exact same time that these muscles are pumping the urethra, the bladder closes shut so the semen won’t be pumped the wrong way into the bladder but rather shoot out the urethra. This is why sometimes it can be hard to pee right after sex.
  • As men pass the threshold of middle age, their pelvic floor muscles become weaker and less semen is ejaculated with less force—even down to none at all. Also, the seminal vesicles tend to empty less completely and may become partially blocked by the prostate gland as it enlarges. These are normal consequences of getting older.

Premature ejaculation

  • Premature ejaculation is reaching a climax and ejaculating before you or your partner desire it, typically within a minute or two of starting.
  • How fast is too fast? Studies indicate that the average duration of intercourse is about 5.5 minutes.
  • Most men with lifelong premature ejaculation come within 1 minute or less. These guys may have an underactive response to the secretion of serotonin.
  • Anxiety itself can cause a guy to fire off too fast. Guys with high levels of anxiety may improve with stress management techniques including meditation. An overactive thyroid mimics anxiety and this can also occasionally aggravate premature ejaculation.
  • A very effective sexercise that can allow you to reset your reflex to take longer before you reach the point of no return is known as “stop-start.” The way this works is you or you and a partner stimulate your penis, make it hard, and get yourself close to coming but just before you reach that threshold you stop, cool down, and then try again. Over time you learn to last longer and longer and eventually graduate from the hand to the real thing.
  • As men get older, nerve endings gradually disappear and it can take more stimulation to get an erection as well as to reach a climax. It’s important for them to understand that this is a normal change so they can reassure their partners that they are not to blame.

Delayed orgasm

  • Low testosterone and low thyroid can also be hidden causes of delayed orgasm.
  • Men who have never been able to ejaculate with intercourse often are affected by some sort of psychological or behavioral barrier. For some it’s an exaggerated sense of guilt or religious prohibition.
  • Other affected men may masturbate in a way that is so specific and so intense in speed and pressure that an actual partner could never provide similar stimulation. Studies find that men who masturbate very frequently are at higher risk of developing this difficulty.

Semen taste

  • What I have found is that there is a small body of evidence that fruits make semen taste a little sweeter and meats make semen taste saltier. This makes some sense since one of the ingredients in semen is fructose, and fructose is the sugar found naturally in fruit.
  • Semen is 90% water, and the more dilute the better when it comes to the palate. Less hydration means more concentrated body fluids and more concentrated saltiness or bitterness.

Penis size

  • The truth is that the vast majority of men have a penis that is normal in length, width, and shape, but they just don’t have any context in which to realise it.
  • Some men’s bodies are naturally configured to hide their penis. They may deposit excess fat around the base of the penis, making the shaft appear shorter.
  • For many studies, penis length is measured by stretching the penis while it is flaccid and measuring from the base of the penis or the pubic bone to the very tip of the head of the penis. There is some variability in what this measurement means.
  • The average size of a man’s penis when soft is about 9cm, give or take 1.5cm when stretched. The average size when erect is a little over 13 cm, give or take about 2cm. The average soft circumference is a little over 9cm, give or take 1 cm, and the average erect girth is about 11cm, give or take 1 cm.
  • Do women really want an 8-inch penis? No, they don’t. According to studies, they actually want penises that are about average. In fact, the average vagina is 9.6cm, give or take 1.5cm, and 2.8-3.6cm wide.

Growers vs showers

  • The reason for this size surprise is based in how the tissue of the penis is formed at the molecular level. The cylinders of the penis that fill up with blood are made out of a special weave of collagen and elastin.
  • Collagen makes the penis tough and durable—like the Kevlar in body armor—and elastin is like the elastic in your underwear waistband. Woven together, this combination makes the penis stretchy but strong.
  • Growers have more elastin and less collagen and showers have less elastin and more collagen.

Erectile dysfunction

  • The most common reason is a problem with blood flow due to narrowing of the arteries. Many conditions can lead to this, including diabetes, high blood pressure, and heart disease. In fact, having trouble getting an erection may be your first and only warning sign of a looming heart attack or stroke.
  • Other reasons: low testosterone; medical conditions and medications; cigarettes, drugs, and alcohol.
  • Most common cause: aging.
  • Men with ED have >50% chance of developing cardiovascular disease.
  • Excess fat lowers testosterone. The fatter you are, the more your testosterone gets turned into estrogen.
  • When you use testosterone, it powers down your testicles. The testosterone that you put into yourself circulates to the pituitary gland, which senses that you have “enough” testosterone and so stops trying to get your testicles to make more. Without the LH signal from the pituitary, the testicles stop making any testosterone at all. The pituitary also stops sending the testicles the follicle-stimulating hormone (FSH) signal to make sperm, and that is why guys who take testosterone get shrinkage of their testicles.

Kegel exercises

  • The squeeze is the movement you make when you are trying to stop yourself from having a bowel movement or peeing. When you’re doing a Kegel squeeze, avoid using other muscles such as your abs or your gluteus maximus (butt muscles).
  • If you stand in front of a mirror when you do Kegels, you should see your penis pull in and lift slightly at the base.
  • A simple variation: hold for 10 secs, release slowly for 10 secs, then repeat. A good workout would be three to five sets of 10 reps each over the course of the day.
  • You can also do short 1 to 2 secs squeezes more frequently, and you can see how long you can hold one long squeeze.
  • Perform these exercises first standing, then sitting, then lying on your back, then on all fours. You can mix it up.
  • For women, strengthening the targeted muscles can increase the tone or tightness of the vagina. They surround the vagina as it passes through the pelvic floor, holding it in place. The added tone in these muscles may enhance a woman’s orgasm intensity because, just as in a guy, these muscles squeeze during her climax.

Peyronie’s Disease

  • Peyronie’s disease, a poorly understood condition of the penis, causes up to 10 percent of men to literally get “bent out of shape.” Although this “disease” is not life-threatening nor does it lead to any other ailments, it can be devastating to the man and his partner as it can render the penis so angled, twisted, or indented that sexual relations become impossible.
  • It’s actually an imbalance. The linings of the chambers of the penis that fill with blood are made of tissue that is both strong and flexible, consisting of molecules that stretch like elastic (called elastin) intermixed with molecules that are tough, called collagen. There is a delicate balance in the organization of these two molecules, but Peyronie’s disease causes them to become disorganized into a nodular mishmash.
  • One known but uncommon cause of Peyronie’s is a syndrome in which other tissues in the body made of a mix of collagen and other molecules go haywire and too much collagen builds up. This is a hereditary condition, and it shows up as nodules and shortening of the tendons in the hands and feet, which are called Dupuytren’s contractures.
  • Another known cause for Peyronie’s is an injury. If the penis’s blood-filled cylinder is injured, the tissue will attempt to repair itself using collagen as a scaffolding until all the other molecules and cells have grown in, but in the case of Peyronie’s disease, the tissue makes too much scaffolding and becomes too stiff to stretch properly.
  • The vast majority of cases seem spontaneous, without any obvious cause. The leading theory is that low-grade damage occurs during sex, like wear and tear on a shock absorber. More men with erectile dysfunction tend to get Peyronie’s and it may be that the penis is buckling a little too much during sex, causing increased strain on the tissue because it is not completely rigid.


  • When an erection lasts too long, that’s called priapism. Blood flows in, but it doesn’t flow out, and pretty soon all the oxygen gets used up, and then the tissue starts to get damaged. This can be permanent. After hours of a big, hard erection, you can actually end up impotent.
  • If you get an erection lasting more than 3 hours, you need to take matters into your own hands. The key is to increase adrenaline in your body because adrenaline will decrease the amount of blood flowing to the penis and reroute it to flow to the heart and lungs. You can get an adrenaline boost from ejaculating.
  • You could also try exercise to boost your adrenaline. If that doesn’t work, it’s time for medication. You can snort over-the-counter Neo-Synephrine nasal spray or take two 60-milligram Sudafeds. These have adrenaline-like effects on your system. If your “head” is still “up,” it’s time to give your doctor a heads-up.
  • Another penis emergency is a fractured penis. A penis fracture is not really a fracture of a bone but rather a rupture of the lining of one or both of the blood-filled chambers that create the erection.
  • When it happens, it really gets your attention. There is often an audible “pop” at the same time that you experience sudden and very sharp pain. You lose your erection because the blood is no longer trapped, but then there are very profound swelling and bruising that make your penis look like an eggplant. This is your clue to get to the emergency room right away!
  • One last emergency that is more annoying than dangerous is called paraphimosis. This is when the foreskin is left rolled back behind the head of the penis too long and it swells up like a travel pillow.
  • Fortunately, there is a simple fix—squeeeeeeeeeze it. You may not be able to “handle” it, but a doctor can. He will squeeze the swollen foreskin flat so that it can be rolled forward. The best policy is to make sure that the old turtleneck is always pulled up nicely whenever you are “outside.”