Abreviated as F.U.C.K.
Back in the Middle Ages, this was a reason to be put to shame. For Unlawful Carnal Knowledge, also known as fuck, was a form of rape and illegal act in the Middle Ages.
A euphemistic way of referring to taboo sex (outside of marriage, adultery, homosexuality, sodomy, etc.), this phrase is often used as a false etymology for the word "fuck"
Also, Van Halen's 1991 album
I remember coming home and getting slapped by my dad for unlawful carnal knowledge, apparently he found out my "roomate" and I were actually dating
While our lifespan is the number of years we will live, our healthspan is the number of healthy years we will have and our sexspan is is the number of years we will continue to be healthy enough to continue having an active sex life.
A lighthearted reaction upon receiving disappointing news of some sort. Usually something that isn't a particularly a big deal, esp. when it primarily affects someone else - sort of a mild schadenfreude. Sometimes doubled or tripled, and possibly said in a sing-songy voice for added comedic effect to imitate a muted trumpet, which is how the meme originated.