Every month in Mileposts there is a lovely little section that mentions etiquette for people riding the trains. Keeping your feet off the seat and to refrain from conversations on cell phones are almost always mentioned. Although I don’t think Mileposts has made note of it, nail clipping on the train is generally frowned upon, and seems to be a pretty big pet peeve of commuters. But what if you could do all of those things at once? You would probably be the most obnoxious train passenger ever. Sort of like this: I’ve always wanted to do this on a...