I sometimes become convinced that random people in the street are making some response to seeing me, even when rationally I can decide it's probably a coincidence and nothing to do with me. Usually it happens when I walk past someone who simultaneously spits on the ground - I feel they're spitting as a response to seeing me; or if they sigh loudly, I feel they must be irritated by me in some way. I only normally notice these things, or worry about them, if I'm in a particularly paranoid mood, though, and usually then I'd just look in the other direction, or try to make myself insignificant. I can just about imagine being in a really foul mood, deciding someone was laughing at me, and addressing them about it angrily. (It's not something I've ever done, but I can just about conceive of doing it.)