To quickly chug the remainder of your glass of beer when someone offers to top you off from their pitcher. This is done to get those extra few sips at the cost of being a douchebag. Term originated at Finnegans Pub in Huntsville AL.
Tourist in bar 1: Hey let me top off your glass. *grabs pitcher*
Local drunk: Wait a sec. *chugs his half-filled glass*
Local drunk: OK, go ahead.
Tourist in bar 1: ...
Tourist in bar 2: Huntsville topoff!