I think you'd be surprised. I don't see why any guard or police force would take issue with someone being definitive about their nos. If someone continues to ignore them, I'd take more issue with that than someone emphasizing their vocabulary with a knee to the naughty bits. I'd say he'd have it coming.

Or, you could just carry around a sign on a stick that says you're not interested and to leave you alone. Either would work. And you can use the sign to beat the illiterate asses over the head with. Again, win-win.