I would throw something juicy that stains, or greasy so it is uncomfortable to "wear". I would say chili cheese fries or nachos. It has got to stain yet feel uncomfortable at the same time. So what happens would be a stain and them hating you for at least a day or two or maybe even forever , but if they already hate you then it isn't a big deal, unless you get in trouble. I would get the chili cheese fries out of the toilet after it has been "used" and attempted to flush down the drain.