The first upskirt I ever saw that really made my heart race was in 7th grade ('88-'89). Short skirts had recently come back into fashion in a big way, and girls and women still almost always wore tights or pantyhose if they were getting dressed up. When I got to junior high, my English teacher thought I was a really good speller and encouraged me to sign up for a spelling bee. I actually made it all the way to state finals, where there was this really cute brunette from the opposite end of the state sitting across from me. She was chatting with the girl next to her, and occasionally crossing and uncrossing her legs. Her skirt was quite short, and she was wearing nylons, so I couldn't help but keep an eye on her. At one point she opened her legs far enough for me to see that she wasn't wearing panties under her nylons. A nice view of the Flatbush neighborhood indeed.
I didn't win the spelling bee, but I like to think I still "won" after a fashion.