I remember parts of a scene, but not the title or author. Reasonably sure it was on SOL, and may have been part of a very long story.
A guy boasts about having sex with a girl (probably high school). The MC confronts the braggart, saying the boast could not be true because at that very time he (the MC) was with the girl and the two of them were involved with something innocuous (maybe studying?) I believe the MC may convince the braggart to withdraw the claim to everybody who heard it.
I realize that's not much to go on, but I've previously queried about lost stories with even fewer details and participants in this forum have come up with the answer. All help appreciated.