I know a paramedic that had to deal with the aftermath of a couple of ********* at their office that decided to fire a CO2 extinguisher into a shower cubicle while one of their colleagues was showering. It was a merry jape until the bloke passed out from oxygen deprivation and smashed his head on the floor, leading to a nasty head wound and blood everywhere.Fire extinguisher? Point horn upwards and pour in a generous quantity of fine white pepper and chilli flakes. Seal horn with paper cut to size and wax to hold paper.
Point at some one and depressed handle.
If you did it to someone like say your mate...who was in some sort of enclosed space like a site porta loo... the effects are quite spectacular... the victim may or may not be rendered in to a crying choking coughing mess...
13 years on the victim of this harmless prank still won't speak to me.
The three that did the deed didn't last long in the company.