BATMAN AND ROBIN
Choose two people to be the bad guys: Penguin, Cat Woman, etc.
Have them turn their back and choose, secretly, a person to be Batman or
Batgirl.  This person secretly unfreezes anyone tagged by the "bad guys."
Tell the "bad guys" that they have two jobs:  to tag as many people as they
can and to find out who is unfreezing people.  The older classes get real
sophisticated with this.  They decide everone should tag everyone who is
frozen but they know only the "real" unfreezer can unfreeze someone.  They
use other techniques too:  don't move immediately after being unfrozen, keep
your eyes on the "bad guys" and not on the "good guy.'  Remind the younger ones not to call out the name of the "good guy."  Have a discussion with the class to find ways to confuse the "bad guys."