The phrase comes from casual internet text speak, where ur is short for your and the whole line reads like a quota warning for talking too much. It spread as a short voice meme on soundboards and in TikTok and Discord edits, passed around as a ruder, funnier version of simply saying stfu. Clips like the bruh sound work the same way, giving posters a one tap reply instead of an explanation. It stays popular because almost every group chat has one person who keeps going long after everyone else has checked out.