While there are likely quite a few surprising things you didn't realize could get you banned from an airline or a train, using a stray curse word is definitely near the top of the list (literally, in this case!) Per the tale, there were even "other passengers who heard it and could confirm it was something I said to MYSELF." In the official Amtrak Code of Conduct manual, "obscene language" is, in fact, grounds for removing a passenger. On Reddit, one user noted that the language used in the situation at hand did not appear to fit the "legal definition" of the word "obscene." It is, of course, worth noting that obscenity can be subjective, and what qualifies as obscene language for one person might differ for another.