Players pantomime throwing objects around in a circle. They should be encouraged to use the object deliberately and demonstratively, showing it's weight or value (or anything else) by the way they handle it. Additionally, this exercise should inspire agreement and acceptance, as an object shouldn't change when it is thrown to another person. If one player is handling something incredibly hot, another player needs to maintain that reality when they receive it.
Players circle up with enough space to move comfortably. The improviser running the game pantomimes reaching into a large bag, and pulls out the Red Ball.
Like Zip Zap Zop, the Red Ball is passed around the group with deliberate focus and acceptance. The way to pass it is as follows:
Player One (as she is throwing, making eye contact with Player 2): "Red Ball"
Player Two (receiving): "Red Ball thank you."
Player Two (to someone else): "Red Ball."
This exchange is important, as it ensures that the improvisers send the objects clearly, and that the receiver acknowledges what she has just caught.
From here, the improviser running the game can pull anything she'd like out of the bag. It's common to stay a little grounded before you pull out crazy stuff, and many people will go from "Red Ball" to "Green Ball" (no obvious difference from Red) to "Lead Ball" (very, very heavy). After that, consider pulling out "piano," "puppy," "fire," or anything in the known or unknown universe.