Shithead (also known as China Hand, Palace, Shed, Karma, Danish or "OG") is a card game similar to the Finnish game Paskahousu. In the game the object is to lose all of one's cards, with the last player to do so being the "shithead".
How to Play
Each player is dealt three cards face-down on the table, three face-up on top of those, and a hand of three cards. The remainder go in a stockpile. Before you begin, players may change any of the face-up cards on the table with the cards in their hand to create the strongest possible face-up trio (twos, 10s and royals are good here). The face-down cards must remain unseen.
Whoever holds at least one three in their hand (or if no one has a three, the person with the lowest card/s above a three) starts. They lay this card (or cards if they have more than one three) face-up to start a new "discard pile", then draw the same number of cards from the stockpile to replenish their hand to three cards. Play proceeds clockwise, with each person laying a card (or cards) equal to or higher than the card on top of the discard pile, then drawing back up to three from the stockpile. If all four cards of one number are played consecutively, this "clears the deck" - ie. that discard pile is put to one side, and the person who laid the last card starts a new pile with any card (or cards) they wish.
Some cards have a special significance. You can play a two at any time to "reset the count". A 10 can also be laid on anything, and clears the deck in the same way as four of a kind does.
If you cannot play, you must pick up the discard pile and add it to your hand; the next player then restarts with any card or cards. When the stockpile is exhausted, just play out your hand. When that's empty, you play your face-up cards, and finally your face-down ones, which you must not look at before you lay (if the card doesn't "fit", pick up the whole discard pile). Last player standing becomes the shithead.
Get more info on how to play the game on The Guardian.