Don't worry about manners if you are genuinely feeling unsafe. Women in particular are conditioned to always be polite, even when we feel uncomfortable. Predators know this, and they take advantage of your good nature. But safety always trumps manners. Don't be bullied into giving out information or agreeing to things you're not comfortable with. If someone is making you feel weird, just leave or tell them to get lost. Don't even worry about looking weird or rude.