A simple game. You're pretty much in your own world at this point. Well...with how you think of things in your mind, I suppose. Not necessarily something real, but not exactly fake. Anyway, you write in second person and basically say something's happened. Then add: Whodunnit? The next person can either say what they actually think/know who's done it, or can think up something preposterous.
1st person: You walk out of the classroom after telling the teacher you need to use the restroom. Walking past the men's, you look at the floor and notice water leaking out from under the door and a constant running sound on the inside. Whodunnit?
2nd person: Great. Mom probably kicked Dad out of the house when he said he had to go and he came here to use the bathroom. Way to clog the toilet, Dad.
You walk by a neighbor's yard and notice their grass is almost completely gone from their yard. Nothing but dirt. Whodunnit?
3rd person: Well, Jamie is a pyromaniac. She probably lit a damn ant on fire and the grass caught the flames as well.
Yes! You get the picture now! Okay, so here I go.
After leaving Starbucks and getting your favorite drink in the process, you look down and notice a stack of pennies sitting on the pavement in front of your vehicle. Whodunnit?