get the crew together & tell them to do a chugging contest with a new beer from germany called ( gelbe saft ). Gelbe saft actually means yellow piss, but don't tell them of course.
Make fake cans and just put whatever type beer of actual beer (Heineken, etc.) in four cans.
Give them the four regular beers to chug first then give them all a bonus beer, and that beer will be the only one filled with piss. This is so that way when they puke, they puke up all of the beer they drank and more.......
And for another kick in the ass just throw a hive of bees at them just to enjoy the moment more ... lol