Whats a prank I could do with an airsoft or cap gun?

Ok, so my friend tried to prank me yesterday and he failed. i caught on imediately and busted him. he said he was gonna try again and i said he cant get me and that id get him first. Whats an epic prank we could do to make him be scared sooo bad?? We have access to a car, airsoft and cap guns, and i few people.. i need idea's!!!