Someone tries to get an advantage in a competition or fight by starting before the signal to go
In any competition, making the first move helps. Naturally, The Combat Pragmatists of the world and those who believe in Fighting Dirty often like to take that a step further, by intentionally getting in a first blow before a competition is even supposed to start so they have the advantage. While an Anti-Hero may be able to get away with this, it's generally more of a villain move. After all, heroes can only get away with creeping out in front of a race's starting line or hitting an opponent that isn't ready in sparring so many times before they stop looking like a hero. If the person doing it loses anyway, it's because Cheaters Never Prosper.