variation of a blumpkin with a very important distinction. sexual act during which a man shits while anally penetrating his lover. the distinction here is that a blumpkin must be on a toilet, whereas a blumpster can occur in any location.
a real pro can execute a pretty logical chain of events between a blumpster, a hot carl, and a blumpkin.
"Dave ate some bad Indian food last night and shit himself while ramming Kate's pooper. It was an accidental blumpster, alright!"