Spiders or any other kind of bug that may be in a nasty lake while skinny-dipping. Named for the small but very frightening possibility that they may disappear into unsavory places on a girl's body where they will lay eggs that will hatch and emerge at a very inconvenient time and place.

When you eat dirt for the first time and leave your family to build a shack in the woods

The spiders that crawl in dirty people coochie when they sleep naked