I read a story, long ago before online stories were a thing, with a similar theme. A guy was dating a girl who for whatever reason wouldn't go "all the way" with him. She wanted to wait for marriage or some such, but he didn't want to marry her, he just wanted to fuck her. So he has her over to his place for dinner, but beforehand, he recorded a special fake radio program. It was all nice music for an hour or so, but then a "special news bulletin" breaks in on the music. An announcer (actually a friend of our scumbag hero) reports that Russian missiles are on their way, and everyone has exactly an hour to live!
The chick decides she doesn't want to die as a virgin, and the two hop into bed and screw like crazed weasels. Eventually, of course, she finds out that it was a hoax. I remember being surprised that she wasn't more upset about the whole thing.
I can't remember the title or author or anything, but it had to be at least twenty years ago that I read it.