Hee! I have a couple of times coached or co-coached one or the other of my son's DI teams. (Destination Imagination--it's sort of competitive improv, crossed with the sort of corporate team-building type exercise where you try to build the tallest tower out of toothpicks and marshmallows.) And during the improv section, they're handed a prompt, given three minutes or so to discuss it, and then have about five minutes to perform. During which the coach cannot do ANY prompting--including involuntary "c'mon, c'mon" gestures to indicate that they're running out of time.

I actually, literally SAT ON MY HANDS.

Maybe you could hold a pen in your teeth or something?