Pairs is a "New Classic Pub Game" by James Ernest and Paul Peterson, who also brought you Unexploded Cow. It's an extremely simple press-your-luck game featuring a deck of number cards (1 x 1, 2 x 2, 3 x 3, and so on, up to 10 x 10). There is only one loser, and the object is not to score points by colelcting a pair.
Another Patrick Rothfuss / Shane Tyree collaboration, the Modegan Deck comes from a far-flung piece of the Four Corners world. The Modegan Pairs variant game, Blackstone, is about as different as a Pairs variant can get. It's like playing chicken for money.