Quite a while back, visiting a male friend in the town where he teaches high school, we ran into a bunch of his kids. These were high school juniors or seniors, and we were (at the time) only 22 and 27 respectively, so we're not even that much older than them.

But the kids walked up to me and my (unmarried) friend, and said "Hi Mr. Smits... oh... you must be Mrs. Smits!" and hearing whispers in the background "That's his wife!"

What really ground it in was that I actually was engaged to him for a while