This is a bit similar to the corrupt your wish game. Someone posts a phrase and the next person comes up with a plot twist for the previous post.

So it'd go like this:

1. Sally has a cute little hamster.
2. PLOT TWIST! The hamster can talk in a deep manly voice.
3. PLOT TWIST! Sally is the hamster!

etc.

The more ridiculous and silly the twist, the better.

So I shall start:

Jack walks to the park.