O_o

O_o is Twitch's mismatched-eyes reaction. Unlike the sideways smileys, this face is read upright: one O is a large eye, the separator sits in the middle, and the lowercase o is a smaller eye. Twitch renders that imbalance as a robot with one eye much larger than the other.

The family accepts O_o, o_O, O_O, o_o, O.o, o.O, O.O, and o.o. TwitchTV was already varying the orientation in 2013: the standard and monkey sets used o_O, while the purple Turbo set used O_o. Older TwitchTV chat also treated the o characters case-insensitively. Twitch now maps those case, orientation, and separator variants to the same confused artwork.

Viewers type O_o in Twitch chat to use this emote. The same family covers the listed upper- and lowercase O/o forms with either an underscore or dot. It fits confusion, disbelief, a strange claim, a baffling play, an unexpected visual, or a moment that makes chat look twice.