barmat shot

The leftover spillage from errant shot pours which funnels into the rubber barmats which bartenders typically divvy out to least-favorite patrons at the end of the night - "Hey, this one's on me!"

A jerk walks into a bar (lousy tipper or loudmouth prick) and the bartenders start "missing" a few pours, especially with more exotic liquors (and lots of them). Eventually, there's enough in the barmat..."I think THAT guy deserves a barmat shot...this one's on me!"