We thought we already had this covered: nail clipping on the subway is not cool, under any circumstances. As it is, we think even nail filing is on the edge of acceptability. But clipping? Between the nails-on-chalk sound and the discarded bits that fly all over the place, it is absurd that we're even having this conversation. And this assumes that we're only talking about fingernails! And yet, in the video below, a man is called a "mental case" for pointing out to a stranger that it's "kinda gross" that he was clipping his nails on the subway.
The two get into a long argument about subway etiquette, but the clipper-in-question calls the request a "ridiculous demand", and refuses to cede his position, saying he has "nothing to do in here."
We especially enjoy this reasonable argument against clipping nails: "If you would like to be a normal human, than you would not do that...These people are normal human beings because they decided, 'I'm not going to brush my teeth on the subway'...that I don't mind, you can file away, just the clipping is really gross. Please don't do this."
One more time: don't clip your nails on the subway, don't have sex on the subway, don't urinate on the subway, and be respectful of noise pollution, physical contact, hygiene, seating priority, garbage disposal (or lack thereof), and of course, eating. But do feel free to put a rat in your mouth if the mood strikes you.