Too many people know that trick -- and that's a
GOOD thing!
The sucker card location will definitely win beer and make enemies! If this is your primary method of obtaining drinks/sex/whatever, you will be disappointed to hear that particular trick is becoming very widely known (to the extent that I can guarantee to see it at least once at every performance. Although you can use this to your advantage.
If anyone ever approaches you in a bar to take this bet (and are not particularly interested in making any friends) go along with it. Pick your card, watch the trick as if you have never seen it before -- even smirk to yourself when the poor trickster passes by your card.
When the bet is laid down to you, insist that the trickster could not possibly turn your card over next (if you think he will pay, raise the stakes!). Once the negotiation is finished, you will need to do three things simultaneously. Reach out to shake his hand with your right hand (looking him square in the eye) and say "You've got yourself a bet" At the same time, with your left hand, turn the entire face-up pile of discarded cards (yours included) face down and give them a good mix, scattering them across the table. Thus rendering him incapable of "turning your card over next"
That will teach him to try and con you!