What are some smartest "cheating" moments in competitions (sports, games, exams, etc)? Not like breaking already existing verifiable rules, or lack of sportsmanship, but the perpetrators did legal actions that felt like cheating, that later forced updates on the rules.

(The intent doesn't matter: they might have done it while knowing it'd break the game, or just because it's legal.)

Best I can think of is in soccer/football where that guy was juggling the balls with his head. Although, this is more about it being dangerous than "feels like cheating" moment, ig.

But it doesn't have to be from physical actions, or skills. It doesn't have to be from sports as well, but maybe esports, games, chess, art, talent shows, exams, etc. Maybe drug related? Or a device? Or a smart plan? Etc.