Haven't had a stranger do this to me and I'm not sure what I'd do if one did. A friend of mine outed me at a restaurant about a month back when, as we were going to pay, she said "Put $xx on this card and the rest on his." You should have seen the waitress' face at that moment, how she instantly shot her head toward me with her jaw half open. While she was gone, my friend was apologizing profusely and I was almost in tears. I'm not sure what the waitress thought after that as she scanned my credit card (and saw the name Zoe), but as my friend and I left the restaurant, the two waitresses said "Goodbye, ladies!" as if nothing had happened.
Then there was the end-of-year celebration at work in May, when my boss was calling out the names of all the tutors leaving the center so that we could walk to the front of the room and get our certificates. I'd been out at work for two months and went by Zoe, but all my paperwork still had to have my boy name because my name change wasn't legal until June 10. But as she called me up to get my certificate, she said my boy name, then Zoe (pronounced it "Zo" too) in front of the crowd of about 75 people, 65 of whom I didn't know. I was in a peacock blouse, skirt, and heels, hair done nice, makeup, everything. Just about killed me, but I went and got my certificate anyway. Then she read a blurb about me and called me by my boy name three more times without correction. It wasn't done on purpose, but I was ready to just sink into the floor standing in front of all those people, who were staring at me, being called by my boy name.
That time, I fought back the tears by playing Angry Birds for the rest of ceremony, not making eye contact with anyone. I didn't stop and get up from my seat until the entire room was cleared out. But I broke into a million tears when I got back to my car.