Ok, i know the movie, its a Peter Jackson movie about aliens but i cant remember the name. Cover of movie has an Alien giving you the finger. There is a scene were a goat or a sheep gets blown up with a bazooka right?
Hang on let me do a search on PJ movies. HA GOT IT, ITS CALLED BAD TASTE!!!!
its about a group of 3 aliens in black trench coats and sunglasses disguised as teenagers, a group of friends find their weird weapons (a gun that fires backwards)
and i think they fight a the end