Example:
I challenge you to get her number. If you get it, you earn a beer.
It's sort of a friendly bet. It's a short 3-5 letter word. I've heard it but can't recall it. Please help.
Something pertaining to: bet, challenge, dare, play, sport, game, toy.
May also relate: a clever move, trick, stunt, tactic.
Best Answer
A word I've heard used in this context is a wager, which TFD defines as:
In this case, the unsettled matter is whether the lady will give the challenged party her number. The challenger is pledging a free beer to the challenged party; if the challenged party accepts, they are pledging to get her number.
Given the casual nature of the bet, this might even qualify as a friendly wager, a phrase whose popularity is shown in this nGram plot.