[PA Engineer]

You can paint it on door frames too. ;-)

[The Duke]

Is this the stuff that makes the little purple mushroom clouds when dropped from the third floor of the dorm by the CHEM-E majors?

[elcid1970]

When I was a college freshman, my roommate painted it on commode seats, which were black, in a bathroom that was for upperclassmen only. One night it paid off with a muffled bang and a scream of “Those little bastards!!”

;^)