:O

:O is Twitch's open-mouth surprise family. In the sideways text face, the O becomes a round open mouth. Twitch's robot artwork makes the reaction even clearer with large eyes and a small open mouth, producing the look of someone caught off guard.

The family accepts :o, :O, :-o, and :-O. TwitchTV's themed smiley sets were already mixing that capitalization in 2013: the standard set used lowercase :o, while the purple and monkey Turbo sets used uppercase :O. Twitch now recognizes both cases, with or without the optional hyphen nose, as the same surprised artwork.

Viewers type :O in Twitch chat to use this emote. :o, :-O, and :-o are same-family variants. It works for a sudden reveal, an unexpected clutch, a shocking result, a jump scare, an enormous number, or any moment that makes an open-mouthed reaction feel natural.