The first things that could “go off” were weapons. Starting in the 16th century, to go off meant to explode in a decisive spurt of energy. Even as the more literal meaning of “to depart physically, to wander” followed close behind, the phrase retained the sudden dramatic shock of its inception. If I go off into the woods, you don’t picture me embarking on a leisurely stroll to pick some cherries and commune with some friendly woodland sprites. The term has never lost the connotation of violent drama, even now, when it’s used to describe a very specific way we communicate in the 21st century.
Go is up there with be as one of the most versatile and abstract verbs in the English language. It takes up about 45 columns of tiny print in the unabridged OED, and can mean anything from “begin” ( “Ready, set, go!”) to “leave” (“My hearing’s going.”) to “speak” (“So I go, ...”) to “price” (“How much does this go for?”) to “urinate” (“I gotta go … bad!”). What joins the various semantic contortions of the syllable is the energy of state-change. To go is to proceed, to move, to evolve. It’s the opposite of its monosyllabic cousin be, though each distills the essence of verbal action into one nuclear two-letter form. At any given moment, you’re either being or you’re going—chilling or making stuff happen. Try to do both and you may tear a muscle.
Add off, easily the most dramatic preposition, and you’ve got the key to semantic ignition: “Change to be really far away” in the rapid fire of two sharp syllables. And on the internet in the mid-2010s, people truly started to go off. Go off first came into the common vernacular sandwiched between but and I guess as a sarcastic flourish at the end of a categorical disagreement. If I read a post saying that bees are scary and bad, I might respond with, “They actually play a crucial role in the global ecosystem, but go off, I guess.” And while to go off on had long been used to describe a strong reprimand, this smug final flourish after owning someone with logic drew the phrase more specifically into the world of internet discourse. Eventually the internet winnowed it down to just go off (as in, “to go on a passionate tirade without concrete structure or purpose”).
As usual, this new sense contains all of the meaning the phrase accrued as it evolved through the years, marshaled to describe the experience of the present moment. When I go off, my words explode with emotion and land far away. The phrase captures a particularly online mode of discourse: replying with an emotional outburst of questionable relevance to the topic at hand. One rant leads to another until the original point has receded into the distance, leaving us alone with the echo of our Wednesday clue: “Response to a rant.”