Capping a bet means changing its size once the outcome is known — sneaking extra chips onto a winning wager or pulling chips off a losing one. It is also called late betting, pressing or past posting, and casinos treat it as outright cheating.
Roulette is a classic target. The croupier calls “no more bets” or signals with a wave as the ball slows, and any chip added after that point is invalid. Cheats have tried to hide the move by pretending to tip the dealer while slipping a palmed chip onto a winning number.
The consequences are severe: a player caught capping is removed, usually barred, and may face criminal charges in many jurisdictions. Casinos counter it with strict betting cut-offs, dealer procedures and the eye in the sky. Online, the risk disappears, because bets lock electronically as soon as betting closes.