What's a penis?

Several first grade boys overheard some junior high boys talking about a penis. The first graders asked each other, "What's a penis?" None of them knew.

Finally one boy said, "I'll ask my Dad, he knows everything."

That evening the boy asked his Dad, "What's a penis?"

The father replied, "Well, if you're old enough to ask I guess you're old enough to know." Dad dropped his pants and said, "That's a penis! As a matter of fact, that's a perfect penis!"

The next day the boy told his friends, "I found out what a penis is, come on, I'll show you."

The others followed him to the bathroom and watched him drop his pants. The boy, exposing himself to his friends, said, "That's a penis! As a matter of fact, if it was two inches shorter, it'd be a perfect penis!"