Meaning
Teeth clenched in a wide, tense grin, as if bracing for something unpleasant. Despite the teeth it is not a happy smile: it means awkwardness, discomfort or the “yikes” feeling of seeing something go wrong.
It fits awkward confessions and near disasters: “Remember the vase you lent me? About that 😬” It also reacts to cringe-worthy moments in shows or group chats. Readers who only glance at it may mistake it for a big grin, so in delicate apologies spell out that you feel bad rather than relying on the face alone.