ghost butthole

The term ghost butthole refers to the last remaining and moat ashy hit in the bowl of a pipe, bong, chalice, or other kind of smoking pipe and typically refers to marijuana smoking. When a bowl is, "cashed," or no longer contains green, it can be considered a a ghost butthole.

"My friend is truly such a cheapskate... he even saves the ghost buttholes and smokes them later!"

Ghost butthole grabber

When you stealthily swim up on someone in the pool and you poke them in the butthole and then say "ghost butthole grabber... yeahhh"

I just got poked by that "ghost butthole grabber"