Masturbate until you're ready to cum, and then run up to the closest person and blow your load on their face? I often enjoy this while on vacation because the chance of getting caught is slim. I couldn't pull it off in my home town though, too small.
I've done it about eight times so far and I think it provides a unique satisfaction.
saucybird
it's best pulled off in crowded city right? because no one is able to notice let alone quick enough to realize what's happening
Suprememessage
Indeed. Best during rush hour. If you're really crafty you can do it from the top of a building and try to get it to land on someone from up above.