From GQ.com….
Did you know Leonardo Da Vinci was apparently the one to discover that blood flow in the penis is what creates erections? Before then, it seems that a lot of people thought that boners filled up with air, like a balloon animal. Now, of course, we know a lot more about the dick than just simply, “it fills up with blood.” One thing we know for sure? Sometimes it doesn’t, even when you really want it to.
