A Three Card Poker side bet paid on your own three cards only.
It pays on a pair or better; the dealer's hand does not matter. The paytable changes the cost a lot: the most common, 40-25-5-4-1, has a house edge of 6.75%, the original 40-30-6-4-1 2.32%, and 40-30-6-3-1 7.28%. If you also have an Ante and fold, the Pair Plus is lost too.