Even though most men are very familiar with their penis, there are still hidden secrets about it that many people don’t realize. In fact, these aren’t just secrets about the penis—they reveal fascinating facts about human evolution itself! Let’s uncover them one by one.

1. The First Erection Happens in the Womb

Did you know that a baby boy can have erections before birth? Ultrasound images often show fetal erections occurring as early as the second trimester. These spontaneous erections mostly happen during deep sleep, sometimes multiple times per hour.

While the exact cause is unknown, experts believe it’s a natural test of bodily functions, ensuring that everything is ready for life outside the womb.

2. Your Penis is Actually Twice as Long as It Looks

The visible part of the penis is only half its true length! The other half is hidden inside the body, extending deep into the pelvis.

3. Size is Not Constant

Penis size is not fixed—it varies depending on temperature, mood, and stimulation type.

• The global average erect length is 5.16 inches (13.12 cm).
• In Thailand, the average is around 4 inches (12.8 cm).

Interestingly, erections achieved through physical stimulation (such as oral sex or penetration) tend to be larger than those from mental arousal alone (such as imagination or visual stimuli).

4. Size Actually Does Matter

People often say “size doesn’t matter, it’s all about skill.” However, studies show that women are more likely to reach vaginal orgasm with longer penises.

Additionally, women often prefer taller men, partly because height is subconsciously linked to penis size expectations.

5. The Foreskin Has Evolutionary Origins

The foreskin initially fuses with the penis in the womb before separating later in development.

• It evolved from the same type of tissue as the clitoris in female genitalia.
• Circumcision has been shown to reduce HIV transmission risk by over 50%.

6. Those Small Bumps? They’re Normal

If you notice small flesh-colored bumps around the glans, don’t panic! They are not sexually transmitted infections (STIs)—just a harmless natural variation caused by tiny trapped blood vessels.

7. Having Multiple Penises is Rare – But Possible!

A rare genetic condition called Diphallia causes a person to be born with two penises—occurring in only 1 in 5-6 million births.

Even more shocking, in 2021, the first known case of “Triphallia” (three penises) was reported!

However, having multiple penises doesn’t increase sexual pleasure—in fact, it often causes severe functional issues.

8. The Penis Can Break—Even Without Bones!

Although the penis does not contain bones, it can still “break”.

This occurs when the erectile tissue ruptures—usually due to forceful or incorrect sexual positions.

The riskiest positions for penile fractures are:

1. Woman on top (highest risk)
2. Doggy style (second highest risk)

9. Erections Happen Every Night

Every night, the penis goes through 3-5 erections.

The exact cause is still debated, but theories suggest:

• It may prevent nighttime urination.
• It is linked to REM sleep, which plays a role in memory formation and dreaming.

10. Your Last Erection Happens After Death

Yes, a dead body can have an erection!

This occurs due to rigor mortis (post-mortem muscle stiffening), which can force the penis to become erect. In some cases, semen can even be released after death.

Final Thoughts

The penis is far more complex than most people realize! From fetal erections to post-mortem stiffness, it holds secrets that reveal surprising facts about human biology.

Did any of these surprise you? Let me know!

Q&A About 10 Secrets About the Penis You Might Not Know!

Q1: Can a baby boy have an erection in the womb?
A: Yes. Fetal erections have been observed on ultrasound and can happen spontaneously during pregnancy.

Q2: Is the penis longer than what you can see?
A: Yes. Part of the penis extends inside the body, so the visible shaft is only part of its total length.

Q3: Does penis size change day to day?
A: Yes. Size can vary with temperature, stress, mood, and arousal, especially when flaccid.

Q4: Are small bumps around the glans normal?
A: Often yes. Small, flesh-colored bumps can be a normal variation (like pearly penile papules) and are not necessarily an STI.

Q5: Can the penis “break”?
A: It can’t break like a bone, but a penile fracture can occur when erectile tissue tears during sudden bending and needs urgent medical care.

MD. Suebphong Angchoun

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