I did. Twice.
First was with my high school girlfriend. We were madly in love and she was pushing for it more than me. I was pretty scared -- It was my first time too -- but we laid a towel down on my shitty bed and "made love." After that, we went at it four-five times a week for the next couple years; lots of pregnancy scares, broken rubbers but, overall, it was very sweet and one of the happiest moments of my life. We're facebook friends now. She still looks great.
Second time, not so good. Word got through the grapevine that my roommate's girlfriend's roommate thought I was "cute." She was a chubby gal but had a really pretty face and a decent enough (although a little too bubbly) personality. As this was the sex and drugs seventies, I figured I'd throw her a fucking or two and that would be it. As I said, she was big so I really had to ride her, so much so that my bed came off the mattress frame -- Crash! Nonetheless, we kept going it till we (I) finished.
I thought that was it. It was a decent experience but I wasn't thinking she'd was girlfriend material. I think I called her the next day but kept any future plans really nebulous. Cut to a few days later and I notice this gaggle of girls around school start giving me really dirty looks. I didn't know what was up until my roomie's girlfriend said I had taken this chick's virginity. She was saving it for a really special guy, thought that was me and I turned out to be just another asshole.
I tried to talk to her about it but unless I made her my girlfriend, she wasn't hearing it. If she had told me she was a virgin ahead of time, I probably wouldn't have went for it but you never know. When I asked her why there was no blood or hymen tissue (I'm a smooth guy), she said she busted her hymen while horseback riding. Seemed plausible but kinda convenient. Still, I believed her and felt bad about it. As she was a really big gal, I also felt sorry for the horse.