Gimme Five is a uncommon Instant card from Unstable (UST), collector number 7. Current market price: $0.22 (foil $0.55), TCGplayer market prices via Scryfall.
You gain 1 life for each person who high-fives you in the next thirty seconds. Each player in an Un-game who high-fives you gains 1 life. (Offer high fives. Don't hit people.)