My friend went to a math camp and brought back a card game called Misha's Bidding Game that is super addicting. I can't find the real name of the game on google though, so I'm guessing it's obscure.
Everyone gets 5 cards, and all that matters is if they are red or black.
Each player arranges them in a stack face down and they go in a circle bidding how many red cards they can flip over from any deck (bids must be strictly increasing).
Anyone can challenge a bid at any time, and the challenged player must flip over from the tops of anybody's stack that number of red cards (you can pick and choose the tops of anybody's deck, even flipping multiple ones off the same deck).
If you successfully flip over the bidded number of red cards, the challenger loses a card, otherwise you lose a card.
If you lose all 5 you're out.
After a challenge, the bidding is reset.
After you've had at least one card flipped or you lose a card, you get to reshuffle your stack