Most of the credit goes to the way my storytelling students and Youth of the Year participants keep changing the "rules."
Here's how it works (at least right now):
Particpants stand in a loose circle, facing inward.
Leader (that would be me) explains that we are going to be throwing imaginary objects at each other, and then says "I'll show you how this works."
Extend hand that is hold and announce "this is a ____"
I usually say spider and use my whole body as well as my voice to indicate how totally creeped out I would be if I really had a spider on the palm of my hand.
I look directly at one of the other participants and say "Name), I am tossing you my spider." Then I throw the imaginary spider at the recipient, who must catch it -- or not depending how she/he feels about archnids.
Once the first toss is completed, I explain that the person with the spider can then throw that same spider to somebody else or else -- with appropriate gestures -- turn the spider into something else.
As we play this game, I encourage everybody to react physcally to the weight, the shape, the safety-danger-creepy-cuddliness of the flying object.
Spiders can become light sabers which can become turtles which can become ... well what would you toss at your friend?
Warning -- arachnid lurking below --not one I'd want to be throwing. He was on my back porch a coule of months ago.