The blue baseball cap is one of the few emoji whose slang meaning is a pun on its name. Billed Cap, added to Unicode in 2017, stands in for the slang word cap, which means a lie.

The slang came first. "Cap" for a lie, and "capping" for lying, is labelled by Wiktionary as originally African American Vernacular English. Its dated citations include an OutKast track from 2003, long before the word reached group chats. "No cap" turned it into an oath: no lie, I'm serious.

Once the hat emoji existed, the pun was waiting. A single 🧢 in reply to a claim is now a complete sentence, that's a lie, and often a funny one. A row of them, 🧢🧢🧢, means the lie is enormous. And "no 🧢" stands for "no cap", the promise of honesty.

That makes 🧢 one of the clearest examples of emoji working as written slang rather than as pictures. Readers who know the word read it instantly. Readers who don't will see a hat and wonder what baseball has to do with anything, which is the main way it gets misread.

It also carries some edge. Telling someone "🧢" is calling them a liar, even if lightly. Between friends it is teasing. To a stranger, or to a manager, it can land as a real accusation.

Credit matters with words like this. "Cap" did not start on TikTok; it came out of Black American speech, and the emoji is a later, playful layer on top.