The Hook

A verb, which means to place ones hooked finger or fingers between another's butt cheeks with an intent to startle, although it is often done in a joking, playful manner between friends. This procedure is normally done while the "receiver" is wearing clothes, although there is no reason why it couldn't be done without clothes.

"Arrrrrr" Llewellyn cried as he startled Stefanie with "the hook" to her behind.