In slang, "clock it" means to call out or expose a hidden truth or someone's real motive in a playful or knowing way. It is often used when someone makes a remark that reveals an unspoken reality, and the phrase is accompanied by a hand gesture tapping the middle finger against the thumb. The expression originated from drag and ballroom culture, where "to clock" someone meant to notice something about them that was not immediately obvious, often something they were trying to hide. Nowadays, it is popular among younger generations as a way to show observational skills or humor, often meaning "busted" or "duh" in a social context.

Additionally, the phrase can be used as a compliment when someone notices something nice about someone else, like their appearance or style, by saying "Oo clock it".