:|

:| is Twitch's flat-expression family. A vertical bar becomes the straight mouth of the sideways face, and Twitch renders it as a robot with closed-looking eyes and a level expression. It reads as neutral, speechless, tired or unimpressed rather than happy or angry.

The :z variants come from an older Twitch shortcut for a sleeping robot associated with boredom, and the z was treated case-insensitively. An April 2013 TwitchTV list used :z in the standard set while the purple and monkey Turbo sets used :| for the corresponding reaction. Twitch now maps the flat-face and sleepy-z spellings to the same artwork.

Viewers type :| in Twitch chat to use this emote. The same artwork family also includes :-|, :z, :Z, :-z, and :-Z. It fits deadpan reactions, awkward silence, boredom, tiredness, an unimpressive result, or a moment that leaves chat with a deliberately flat expression.