Had an online date way back before it was cool...to this day nearly 30 years ago, she was still one of the most physically attractive women I have ever met. She was really conservative and very immature (just moved out of her parents house at 25yo and her parents were paying for her apartment and impressive sports car because she had never had a job yet). Anyway, after dinner we went back to her place to watch a movie, which was her idea. I could already tell that I was friend-zoned, but I decided to roll with it.
We get back to her apartment (she had one other roommate), and she showed me her bedroom as though she was still in college and it was her dorm. She laid down on her bed and said it was so comfortable. It was like hanging out with a cousin as a kid; it was really awkward. Then she said she was going to put pjs on. Took off her top and bra (but faced away from me) and put on a very unflattering pj top. Then took off her jeans (I just saw her black underwear from behind; non-descript), and she put on unappealing pj bottoms.
Then, instead of a movie, she showed me her photo album from a trip to France that she just took. In the album, I saw all these photos of her friends topless on the beach. I asked if she went topless, and she was like, "No way! No guy will see my boobs until we are married!" Yet she literally just changed her clothes in front of me and we had just met a few hours ago. I only saw her from behind, but still.
Anyway, she acted like she wanted a kiss as I was leaving, so I kissed her, and it was like kissing a cement wall. It was the worst.
So, definitely the most memorable, even if not for reasons that this thread was started.