Not quite hangar rash, but one of the funniest things I've ever seen happened at my first line service job. Looking back on it I probably would have done the same thing if I was in his shoes and it was pretty scary to watch but now it's hilarious.

A student was going out for a solo in a 152 and flooded the crap out the engine. Fuel was just pouring out of the cowl. After about 5 minutes of cranking it lights off and this huge fireball envelops the aircraft.

The student freaks out, jumps out of the aircraft while the engine is still sputtering. It finally dies, but not before this student can grab a fire bottle, stick it up the exhaust and squeeze the trigger. The result was the 152 being down for about a month getting an engine overhaul.