Munchkin Lite
Go down in the dungeon. Kill everything you meet. Backstab your friends and steal their stuff. Grab the treasure and run.
Munchkin Lite has all the same dungeon-crawling, pun-making, backstabbing madness of original Munchkin, but with 115 cards, it's the perfect size for three to four players. Take it anywhere, and play it in an hour!