Oops
When I was in my 6th form of school (far too long ago now) the 6th form common room was in a seperate small old building from the rest of the main school. One day two little machines (about the size of a shoe box) appeared in there which seemed to be sampling the air. Me and a mate thought it would be really funny to tamper with them and broke of some small bits from these asbestos type boards that were behind the radiators (they were like the ones you used to put your bunsen burner on. We then crumbled these bits into the bit of the machines that were obviously sucking in the air.

After this I just went home for lunch thinking nothing more of it. Later that day I got a very panicky call from my fellow saboteur saying that the building had been evacuated and shut. I went up to the school and there was red tap over the door saying "Hazardous - do not enter". The machines had recorded massive levels of asbestos in the atmosphere. Within 6 months, the building had been demolished and re-built.

I bricked it for about 6 months after that, convinced I was at least going to get expelled or sent to jail or something. Luckily niether happened. And we got a brand spanking new common room!
(Tom Jones's Mojo Hasn't had any since, Fri 27 May 2005, 16:56, Reply)