SMORc is a well-known Twitch emote and is mostly used to provoke or annoy a streamer into action. SMORc stands for "Space Marine Orc" and is represented by the face of an orc from the shooter Warhammer 40,000: Space Marine.
Although it is relaxing to the Warhammer cosmos, it gained prominence primarily through the Hearthstone community. In a Hearthstone context, it describes a player who "goes face", i.e. attacks the enemy hero directly, which describes a very aggressive play style.
The exact origin is unclear, but the first records can be found in 2013 on 4chan and in archived chat logs from justin.tv. In 2015, the term SMORc and the corresponding image became more and more popular in the Hearthstone community and finally reached the next level through the track "SMOrc Song - Face Never Trade" by DJ KARL THE DOG. The hype in the Hearthstone community eventually led to the term slowly but surely entering the Twitch mainstream.
Since its great hype in 2015, the meaning of SMOrc has changed slightly and now also basically describes rash actions. Hearthstone fans continue to use the word primarily when a streamer plays Hunter or for an aggressive play style.
More broadly speaking, the emote is primarily used more as spam, mild insults, or as leverage. For this, the SMORc emote is often posted in the chat in combination with capital letters and offensive statements.
In addition to being used as a mild insult that someone is annoying or obnoxious, SMORc is primarily used to appear annoying or insulting as a viewer. Often Twitch users use the image as leverage to get streamers to comply with their requests or do what they are told. If the streamer does not follow the instructions, the emote is spammed into the chat by the viewers as part of a small revolt.