moon_custafer | Useful Alternate Tactic:

If you see a woman being bothered in public by a guy using the timeworn “stick to innocuous comments so she can’t ask to be left alone without looking paranoid or rude” tactic; and for some reason* you can’t use the “pretend to be a friend of hers and hope she gets what you’re doing and plays along till you can both escape” gambit—

Try sitting down beside him and every time he starts to ask her a question or make a comment, interrupt him with a “and how’s YOUR day going?”, “Nice/terrible weather we’re having eh?” or “How ‘bout that local sports team?” They’ll both realize you’re doing this deliberately, but now you’ve got him in the conversational vice he was trying to use on her. If you happen to be a man, and larger than him, so much the better object lesson; if you’re a woman you’ll probably have to settle for taking some of the pressure off her and letting her see someone has her back. OK, and the pleasure of paying back the guy, a little bit.

*e. g. you’re also a guy, and she might not feel any safer talking to you; you’re just not up to that much playacting; or you don’t have the nerve to try it without signalling her first, but you're behind her and can’t catch her eye.