We're having a special visitor next weekend - the Journal of Irreproducible
Events, the esteemed (?) magazine of humor in science.  As a part of the
irreverence, I'm hoping to put on an improbable science show, featuring
silliness like giant bubble monsters and  clock reactions.
Can anyone suggest a fun, fairly low-mess demonstration they would
include on such a distinguished program?
 
Thanks for any suggestions,
Jim Moskowitz
-Public Programs, The Franklin Institute-