Troll the other Clans, for examples, read below:
Blame ShadowClan for stealing prey, when they didn't
Blame WindClan for stealing your Clan's kit
Push a RiverClan cat in the water and see how long he can last before passing out
Push an unprepared SkyClan cat off a tree
Invade ThunderClan, than say it was an 'misunderstanding' and that they thought they were ShadowClan, then start blabbering how you really can't ell the difference