Dodgems are a ride at a funfair: small electric cars on a fenced floor, and you drive around trying to hit the other cars, or to miss them. In British English the ride is usually called the dodgems — almost always plural. In American English people say bumper cars. Children love them; adults ride them too, laughing and pretending not to crash. The cars are slow and padded, so it is noisy fun, not a real accident. You may also hear dodgem cars for the little cars themselves. This probably comes from dodge + 'em (them): you try to dodge the others. Though actually, people still say "the dodgems" even when they spend the whole time ramming each other rather than dodging.