It is simple as said, sharing is caring. The word can be use when someone replace a pronounce that are you/your/them/they/he/him/his/her/she and lots morew pronounce to the word "OUR", usually captialize on internet. This can also be used when someone accidently/purposely said the world USSR/Union of Soviet Socialist Replubic/Soviet Union. Also applied at some words such as gulag, stalin, AK-47, PPSH-41, all short of Russian thing.
Note, Russia and Cuba are not communism, Russian federation PROBABLY a democracy state and Cuba is Socialism. Vietnam, Laos, Cambodia too. China is the only one to be officially Communist.
probably like this somewhere on the internet:
A: My car is working nice!
B: OUR car is working nice.
C: Communism moment