When you place a side bet of 21+3, you have a good chance of getting a 21+3 hand. The payout from the side bet depends on your hand falling into place. For instance, if your chances of winning a hand decrease, the odds of the game increase. For a flush, you're likely to win a 5/1 payout. A straight hand has a payout of 10/1, while three-of-a-kind has 30/1. Payouts vary from one casino to another.