Dirty Johnny's sitting in class and the teacher says, “Alright class, today we will move onto sex education.” She then goes up to the blackboard and draws a huge penis. She says, “Can anyone tell me what this is?”

Dirty Johnny stands up and says, “Yeah I can tell you what that is. It’s a penis and you know how I know? My old man’s got two of ‘em.”

The teacher says, “Two of them? Are you sure, John?”

He says, “Of course I’m sure! He uses the little one to pee and he uses the big one to brush the babysitter’s teeth!”