The story
Abbreviation of Space Marine (name of a 2011 video game) + orc. Popularized by the 2015 YouTube video "SMOrc SONG - Face Never Trade" by DJ KARL THE DOG.
Etymology from Wiktionary, CC BY-SA 4.0.
SMOrc
Today it means: The strategy of aggressively attacking the opponent, especially while disregarding enemy minions. Full definition →