This is when you overreact to something, which causes you to first punch somebody (P), then kick them with your non-dominant foot(K), then punch them again(P). Then if you really want to overreact, you storm out (SO).
This is used when you want to make everyone think you're a drama queen (or king).
Remember: These hits are in no way supposed to actually hurt the person, unless you want to get PKP'd yourself.
Guy 1: Sorry man, condoms don't come in extra small! *laughs*
Guy 2: *Fuming* PKPSO's him
Guy 1: ...seriously?
Everyone in the room: That guy's a dick.