Fighter taunts opponent, then gets knocked the f out
Boxing greats like Muhammad Ali and Sugar Ray Leonard taunted opponents by pounding their chest and sticking out their chin. They were quick enough to recover. This fella was not.
During the Ultimate River Throwdown in California, Dan Lewis did a lot of clapping after taking a hook to the face. It was quickly followed by a brutal one-punch knockout. A knockout that sent Lewis to the mat in a faceplant.
Gloriously dumb seems like an apt description here.