I never really dealt with this problem until I moved to New York City, where it seems men from all walks of life and ages often felt the need to stop me in my tracks by telling me to smile.
I don't think a man can understand how infuriating it can be to be asked to smile when you're in the middle of something — like thinking, daydreaming or just zoning out. Why should I smile at you, I think, just because you asked me to. Shouldn't I smile when I feel like it? It's invasive, it's sexist (women are supposed to always be happy and pay attention to men), and basically, it's just annoying.
I tended to ignore them, which sometimes then made them angry. "Bitch," they'd say. Or maybe, "Why so unhappy?" Sigh. How do you react when a man tells you to smile?