First coined by the great Lewis Carroll in Alice's Adventures in Wonderland. This is a race whereby a race course is marked out in an arbitrary shape (a sort of circle was used in the book, but the shape doesn't really matter) and the participants proceed to run the course at their leisure, starting and stopping when they like. The purpose of this race in the book was to dry the participants after a dip in Alice's salty tears.
The race ended when the Dodo stopped and declared it to be finished. The dodo, after much consideration, declared everyone to be the winners and issued prizes accordingly.