What kind of punishment are we talking about? I myself have done some bets - if I use the safeword within a certain amount of time, I lose the bet, if I don't I win. Helps making it more interesting.
But if you don't perceive it as a game, maybe you are taking things too seriously.
Some extra additional time of tickle 🙂 or anything i will judge harmless but disliked by the ticklee in order to deter any misuse