Everyone has been in a situation where someone is doing something that annoys you, be it breathing loud or clipping their toenails on the carpet, this is life. So you might say "Hey quit it" or if you're from Australia "Oi mate" or even Texas "Get to stoppin'." In truth no saying is better than any other but it's funny how different we are.
Anyway, most people are rational and do things they think are ok or right. So when someone is clipping their toenails on the carpet they think it's ok to do, so if you ask them to stop they can't get mad at you or act like nothing is wrong. This is because of differences in expectations/norms which applies on both sides of the toenail clippings. Inversely, if someone know's what they're doing is disgusting or simply annoying, they should expect to be asked to stop, so they really can't get mad either. Note: I've been thinking about this because of recently being thrust into awkward dorm room living.