A few years ago I was at a second had bookstore with my wife. She is about 5'4", blonde, and was wearing jeans and a plain black t-shirt at the time. There weren't many people in there and I ended up with my head buried in a bok for a while and kind of lost track of time. So then I went back to where my wife was standing - she was facing towards a bookcase, bending over slightly to pick up a book exposing a little flesh between jeans and t-shirt. Since there was no-one around I slipped my hand into the gap between t-shirt and jeans, and with my hand resting on her hip / arse, lent over and whispered in her ear "come on babe, let's go".
At this point she turns around and I realise IT'S NOT MY WIFE. This complete stranger gives me that "what the fuck are you doing" look and I quickly withdraw my hand and stammer and stumble over my words and say something a long the lines of "Oh my god, I'm really sorry I thought you were my wife", "you just look the same, see!" and turn around and point to my wife who is standing in the next aisle wearing the same jeans and black t-shirt with the same blonde haircut.
At this point, she turns around and i realise IT'S NOT MY WIFE. Again. What the fuck is going on. She gives me this "don't drag me into this you crazy pervert" look, which I remember vividly to this day. I am beyond embarrassed and just confused now, so I pretty much run out of the bookstore and find my wife standing outside talking on her phone. I grab her and drag her back into the shop "THIS IS MY WIFE" I shout like a crazy man "LOOK, SEE I'M NOT A PERVERT, AND WHY THE HELL ARE YOU ALL EXACTLY THE SAME SIZE AND WITH THE SAME HAIR AND GLASSES AND WEARING EXACTLY THE SAME CLOTHES?" The doppelgangers (or is that tripplegangers?) all kind of looked at each other and then all realised what had happened and had a good laugh at my expense.