Even though you and your penis have spent your entire life together, shared a lot of experiences, and been through many ups and downs, do you really know everything about it? Here are some facts about the penis that you and many other men are probably not aware of:

1. Penis length and shoe size have no relation to each other at all.

Have you heard some guys say that the size of your penis is proportional to the size of your shoes? Do you think it is true? According to some research studies, this idea is totally a myth. Penis size is determined by a number of factors, such as genes and pituitary gland health. The AR gene found on the X chromosome is believed to have an influence in regulating a man’s penis size. In addition, if you experience a deficiency of gonadotropins, or the pituitary growth hormone, or suffer from androgen insensitivity, you are likely to have a small penis.

2. The penis does not have any muscles.

Did you think that because the penis is sometimes dubbed the “love muscle”, it contains muscles? The truth is the penis is not made up of muscles nor is it a muscle. It actually consists of spongy tissues that are filled with blood sinusoids. Every time you feel aroused, the arteries in the penis expand and allow more blood to flow into these sinusoids, resulting to an erection.

3. During an erection, a small penis gains more length than a big one.

One research study observed the penis measurements of more than 2,700 men before and during an erection, and it found that those with smaller or shorter penises experienced an 86% increase in the length of their penises, while those with bigger and longer penises only had a 47% increase in length. Moreover, a different study noted that a short penis sees a significant difference in length when flaccid and when erect, by approximately 1.2 inches or 3.1 centimeters, while a long penis only gets a difference of 0.67 inches or 1.7 centimeters.

4. Your penis can experience multiple erections at night.

Waking up with an erection is a common natural phenomenon that men have. But, did you know that this “morning wood” is the last erection in a series of night erections? According to a study, a healthy male human being normally gets between 3 and 5 erections while asleep at night, with every erection lasting about half an hour. What causes these night-time erections, you ask? Researchers have not found an answer to that yet, but they are looking closely at the possibility of a link to the rapid eye movement, or REM, stage of sleep, when dreaming also often occurs.

5. Your penis can break.

Do you like being adventurous with your sex partner? While trying new positions can be fun and exciting, it can also put your penis at risk of injuries. If erect, your penis becomes more likely to suffer from breaking. There is a good chance that the tubes filled with blood burst if it is violently twisted while hard, and you will experience severe pain and swelling. Sometimes, breakage also happens if your penis slips out of your sex partner without you noticing it and is bent, or if you vigorously masturbate and cause a self-inflicted penile rupture.

6. Fetal erection is a thing.

Many ultrasound scans have shown fetuses having a fully formed erection. And, when it is time to exit the womb, some of these babies have erections too. According to a medical research, these incidents, which are known as fetal erections, typically happen multiple times per hour and commonly take place during a fetus’ REM sleep. The cause is still unknown, but experts think it is the human body’s way of checking if bodily organs and systems are functioning before and after birth.

7. An erect penis can point in any direction.

Do you worry that there is something wrong with your penis every time you see that it curves a bit to the left when erect? You should relax and take a deep breath because it is natural for penises to point up, down, forward, left, or right during an erection. A study that examined the erections of more than 1,500 men found that only about 5 percent had erect penises that pointed straight up, approximately 10 percent had erections that pointed forward, and the rest curved either to the left or to the right.

8. The largest penis in the world is 13.5 inches or 34 centimeters long.

In 1999, American actor Jonah Adam Falcon gained popularity for his penis size, which measures 13.5 inches or 34 centimeters in length when erect, and 9.5 inches or 24 centimeters when flaccid. In his interviews, he has claimed to suffer from lightheadedness when getting an erection due to the large volume of blood that flows to his penis, and that his foreskin is large enough to envelop an entire doorknob. In 2014, he consented to donating his penis to The Penis Museum, or the Icelandic Phallological Museum, in Reykjavik, Iceland, which is home to the largest collection of penises in the world, when he passes away.

9. There are men born with two penises.

Diphallia is a condition where a man is born with two penises. It is a very rare medical developmental abnormality that occurs in 1 of 5.5 million males in the United States. The first case was documented in 1609 in Bologna, Italy, and, today, the total number of reported cases has increased to about one hundred.

10. An active penis promotes better overall health.

Sex offers similar benefits to exercising and working out. Many studies have found that having sexual intercourse even at least once a week can have a positive effect on a man’s health. According to data gathered, sex can lower your risk of stroke by about 50%, diabetes by approximately 40%, and heart disease by 30%.