When I was little we used to play Tennis Elbow Foot. Each person would say a word, and the next person had to quickly say another word related to it, with no repeated words. Take too long and you're out. Repeat a previously used word and you're out. So the game would go something like:

Tennis
Elbow
Foot
Inch
Worm
Bug
Computer

etc. etc.

Quick and easy to learn for kids. Requires no equipment or game pieces. Can be played until only one person is left or you get where you're going.