Perhaps 20 years ago, when I was recently married, my (now ex-) husband and I went to a business dinner event. Another spouse at the dinner became aggressively convinced that I might actually be an actress I'd never heard of, from a slightly trashy show I'd never heard of. (Mitzi Kapture, from Silk Stalkings: http://tinyurl.com/37utacw)
He perseverated on that issue the whole evening, which was not fun.
This was in the pre-internet, pre-computer-in-every-household era, so I had to be clever to find a picture of this woman. When I did, I understood that there was minimal resemblance (dark hair, light eyes) and that he was just demented.