actually it came from when the USSR sent tanks to Hungary to keep down a workets revolution against the Soviet backed regime in the mid-twentieth century. Origanally it was used as a description for divisions in the British communist party between those who felt a global [Soviet backed] communist plan, versus those who supported independent worker collectives democratically deciding their own direction.
Now-a-days it is used to describe anyone who supports leftists authoritarian regimes, whether it be China, or people who act like Russia is secretly Communists, etc. Or just an insult from one leftist against anothet leftist. Like one U.S. southerner insulting another by calling him a liberal.
Should I stay or should I go?
I feel like I should know this