When they are not home, go into their apt and take the toilets.. undo the plumbing from the back and unscrew the toilets from the floor. it's very easy to do. what you do with the toilet is up to you. keep it for a day, put them on his front lawn, set them up in his living room... options are limitless
Could also do something as simple as letting go like 100 crickets in his bedroom. Crickets cost like 10 cents at petstores
