I remember a game on a forum (BitF?) where you'd name two items and then the next person has to combine those items into a new one.
Here's an example
Me: I put in a sausage and a dog.
Next person: You get a dachshund. I put in a a stick of butter and an insect.
Next person: You get a butterfly...
And so on.
If you want, you don't have to make such obvious combinations, you can make your combinations as crazy as you please...
I put in a person and an entire cake.