Echidnas are odd, even for cousins of the duckbilled platypus. They have no nipples, no teeth, and a four-headed penis. But the weirdness doesn’t stop there.

Test your knowledge with amazing and interesting facts, trivia, quizzes, and brain teaser games on MentalFloss.com.

Jun 05, 2013 · Let’s face it, penises are sort of weird. We don’t know a ton about them because we don’t have them (obviously), they’re seemingly uncontrollable snake-like body parts hanging off of a dude and also they just look really funny.

Things You May Not Have Known. Explore our article that reviews penis facts. Unlike women who need a mirror and a yoga position, the penis is a very accessible organ to the men whom they belong to.

We reveal the penis myths around size. Info on penile physiology, biochemistry and anatomy.

Penis Size . We’ve all heard the saying “It’s not what you’ve got, it’s what you do with it that counts.” But somehow it doesn’t make any difference, does it?

85 Penis size facts. Examples: Women find small penises frustrating, annoying and embarrassing. Women are impressed by men with big penises. They look up to them and find them more masculine.

Fun and interesting facts, trivia facts, Did YOU KNOW, useless and useful facts, fun random facts, trivia facts, useless knowledge. Facts Mashup!

s Interesting Facts. Just one cow gives off enough harmful methane gas in a single day to fill around 400 liter bottles. Cows can have regional accents

So does size really matter? And while we’re at it, what exactly is the average penis size? Here’s an in-depth look at how to measure your penis, whether your penis size is above or below average and how to make your penis bigger.