When the use of a 'fun fact' backfires, as the receiver of said fun fact considers the information to be common knowledge. A play on the phrase 'fashionably late.'
Girl: "My boyfriend always falls asleep after sex, it's so annoying!"
Girl 2: "You know, there's a chemical reaction in mens' brains that causes them to be sleepy after an orgasm? Fun fact!"
Girl: "...Yeah, you're factually late, I've heard that about a million times. It doesn't change that it's annoying."