"18" inside a circle with a slash — the age-restriction rating symbol, used to flag adult content, R-rated jokes, or NSFW posts online, often half-jokingly at the end of a spicy tweet. It's one of the few warning emoji that gets used ironically as much as literally, functioning almost like a wink-wink content warning. The design mirrors real-world film and video-game age-rating badges rather than any single national system.
Keywords: 18, age, eighteen, forbidden, no, not, one, prohibited, restriction, underage