Wore a Beatles shirt to an Avenged Sevenfold concert. Ended up putting a jumper on over it...in the middle of a large, sweaty crowd...at a show with regular pyrotechnics, shit was hot yo.
Participated in a throwing war back in the Scouts. No aim, just two teams on either side of the basement throwing anything and everything at each other (I left with many bruises that day).
Covered myself with bird-seed in the middle of an utterly pigeon filled square once (did the same thing with crackers and deer once too, those things ram).
Flipped a kid 180 degrees vertically once (he asked me if I knew any moves 'cause I was wearing my old Tae Kwan Do outfit to some fancy-dress thing back in primary school, grabbed his arm and twisted it nonchalantly not expecting anything to happen).
I used to stand by the road-side when I was three and play a version of sweet and sour wherein I pulled down my pants at every sour car. Admittedly that's more stupid than extreme.