One of the most common is what I call the “state the obvious” encounter. You’re on a bench waiting for a bus, in a cafeteria, at an office, in a classroom, at a coffeeshop, riding a subway or a ferryboat and a complete stranger comes along and states the obvious. “You’re reading really close up.” “Your eyes look weird.” “Wow, your glasses are really thick.” “You’re blind!” “Is that a blind dog?” (to which some people, hearing this over and over, learn to reply, “I sure hope not!”).
Or there are the oddball questions. One time I was reading a quote on a small piece of paper, close up, and some stranger asked me, “Oh whoa, are you listening to the paper? That’s so interesting.” What?!