Rock Paper Scissors
Meet Lenny. He plays Rock Paper Scissors with you. BUT he literally can't see your hand, so he trusts you to honestly call each round.
Here's the thing: Lenny's never lost. Not once. Best of three?
You may throw Rock, Paper and Scissors ONLY ONCE each across the 3 rounds.
Since he can't see you, Lenny just repeats whatever throw he likes and trusts your honest call.