My SIL told me about an episode of Oprah where some Doctor was talking about Pin Worms. She then decided to tell me all about them. It's pretty nasty stuff. It's some sort of worm, that gets into your intestines, and then crawls out your ass and lays eggs at night. EEEEEWWW!!! She really needs to stop watching crap on television. :o) I'll be thinking twice next time my ass itches that's for sure!
Those of you with children should be super interested since they are considered extremely common in American Children.
Here's a link for you to get your read on.