bum trickery 

penetrative sexual intercourse of the anal variety

hey freddy, you up for some bum trickery

bum trickery by Josh February 17, 2005

Bumthickery 

A plump round bottom generally attached to an attractive female.

Damn, did you see that girl? She had some serious bumthickery going on.

Bumthickery by Bacon Mustache February 8, 2015