Each person, going round the circle, must say one letter. After the first letter, you must add a letter which could go after that letter to form a word, but never complete the word. Eventually one person will be forced to complete the word or make one up. If you suspect that no potential word is possible after one person's letter, you may challenge them. Anyone who finishes a word first gets a 'D', then an 'O', etc. until it spells out Donkey.