Oh I actually have something for this!

We were at my grandfather's funeral back in 2002. I would have been about 11. I had a cousin around 15-16 at the time and while the older folks were preparing for the ceremony, myself, the cousin I mentioned and some of my other cousins and siblings were in another room near the basement, waiting for it to start.

So we're down there, hanging out, pretty bored considering we were all pretty young and didn't really know what was going on. My cousin is very bored and starts fiddling with stuff in the room. I hear a click noise followed by sloshing sound and then screams from the other kids. My cousin had grabbed the fire extinguisher and decided to start spraying it all over the room.

The poor saps closest to him are covered. He's grinning, they're screaming, I booked for the door and got out as it sprayed into the hallway.

The priest comes downstairs to see what's happening and sees me standing there in the hall, frantic, white foam seeping out from the room behind me.

Didn't do anything. Got spanked by mum when I got home. Cousin did not get punished.

R.I.P. Grandpa, hope you haunt that asshole

TL;DR: Crazy cousin desyroys family members with fire extinguisher while parents are preparing for grandpa's funeral.