21 card trick
you deal out three piles of seven,explaining that these numbers are magical and add up to another magical number:21. then you have a pile selected and a card from that pile memorized. then you pick the piles up and have them tell you wich pile their card is in.you do this twice,then deal out cards and reveal their selection
it doesn't matter what card it is or what pile, as long as you remember to place the pile with their selection in the middle. after doing this three times,deal out cards face up and memorize the eleventh card (their selection). take no note of this and keep dealing until you have only a few cards left. then say "how much will you bet that the next card i flip over will be your card?". They, knowing that their card is already on the table, will probably wager a fair amount.Then reach over and flip the card you memorized earlier. They are amazed and you won some money!