h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

You need a deck of cards (or two, but one is easier) and at least 3 people. However, if you get more than 8 or 9 people playing, each person has only a few cards.

Shuffle the cards, and deal them out as evenly as possible to each player. Pick someone to go first. They should look through their cards and put down all the twos they have, saying how many they're putting down. For example, if they have three twos, they put them face down and say "Three twos." The next person (it helps if you're sitting in a circle) puts down all their threes, and so on. (After Kings, do Aces, then twos again).

If you don't have any of the number you are supposed to put down, you can fake it. You can put down a three and a four and say "Two fours." Or two threes, or a King and a ten... you get the idea. But keep a straight face. If someone thinks you're bluffing, they can call out "Bull!" The cards you put down are turned over. If you were bluffing, you have to take all the cards in the pile back (even the ones you didn't put down). But if you were telling the truth, the bull caller has to take all the cards.

The object of the game is to get rid of all your cards first, and it can take a while. My friends and I always play Bull on the bus on field trips!