Ok this actually happens to my friend not so long ago, he is going on a boxing match and he will bet for the heavy favorite, then suddenly an unknown guy whisper to him, that the fight is going to be fixed and he supposedly heard it from the favorite to win, locker room, are you going to listen to that and bet for the underdog.
What's your take?
My action will depend on who this person who tells that is.
If he is a reliable or I know that he knows then I would change my bet. At least, I would place 2 bets for both results and make profit in both ways without any real stress.