Penises are twice the size people actually think they are

What's the average penis size? You might have heard that it's around five inches if you listen to relatively reliable sources - if you've been hearing anything higher than six and a half, know you're either surrounded by some impressive specimens, or liars.

So, when considering the studies that contribute to those figures, around five inches while erect isn't exactly wrong. However, this only accounts for what's outside the body.

Though it hangs loose and ready for action on the outside, the penis does actually have a lot going on inside, too.

Though typically relatively straight on the outside, erect penises are actually shaped like a boomerang when taking into account the part inside the body.

The hidden part of the penis includes the 'root', which is tucked up inside the pelvis and attached to the pubic bone.

That doesn't mean you can start going around telling people you're concealing 10 inches under your belt, though, because that hidden section isn't likely to make any appearances in the bedroom. As Williams points out, it needs to stay connected to the rest of the anatomy, so it's 'probably best it stays put'.

No matter the length, though, it's important that penises get to stand to attention regularly, as Kohler explains it has to be 'exercised' with erections to stay in shape.

The rush of the blood can help enrich the muscle with oxygen and therefore help maintain its health, and even if men find themselves in entirely un-erotic circumstances, Kohler has assured that the brain can lend a helping hand by causing a erections during sleep.