Take pictures of different kinds of shoes lying on their sides so you just get a shot of their sole, ie clogs, flip flops, sneakers, boat (deck) shoes, high heels etc and see how many can be identified in 1 minute or less. For humors sake you could throw in a picture of a horse shoe, a shoe horn and even a Dealers shoe (used to deal playing cards) or anyother kind of "shoe" you can come up with.