1. Something you have hidden up your ass. Most of the time when your hiding it from authority. After you keestered something, whats in your ass is your ass stash
Example: Prisoner #1-You still got that ass stash?
Prisoner #2-Yeah, I keestered that shit. We got some weed for later.
You climb butt naked to the the top of a couch that has been tipped on its end or a ladder or similar elevated perch, jump, spread your ass cheeks mid flight, and land on the face of your buddy (or new friend) ass first.
I met a girl at church last week. I finally got the nerve to ask her on a date tuesday night. It went well...skeet shooting....mexican buffet ...flying asshole smash.