What i do doesn't really fall into any of those categories, maybe screwing around i guess.
I prefer to sit back at one window away from everyone else who's camping so i don't get bothered much, then when everyone's down run in and kill the zombies, revive everyone, and return to my unseen corner just to keep them all confused on what im doing out there by myself.
As well as how i keep coming out of no where, saving them, then disappearing.

Kiinda mixes in being a team player, and having fun messing with randoms and/or friends.