That refers to funny image macros and means that generally videos and screenshots are not allowed. Exceptions include explicitly humorous and short videos, as well as (social media) screenshots depicting a funny situation, joke, or joke picture relating to socialist movements, theory, societal issues, or political opponents. Examples would be the classic case of humorous Tumblr or Twitter posts/threads. (and no, agitprop text does not count as a meme)

Try to keep an open mind, other schools of thought may offer points of view and analyses you haven't considered yet. Also: This is not a place for the Idealism vs. Materialism or rather Anarchism vs. Marxism debate(s), for that please visit c/AnarchismVsMarxism.

as well as condemning (their) imperialism, even if it is of the "anti-USA" flavor.

That includes so called: Social Democracy, Democratic Socialism, Dengism, Market Socialism, Patriotic Socialism, National Bolshevism, Anarcho-Capitalism etc. . Anti-Socialist people and content have no place here, as well as the variety of "Marxist"-"Leninists" seen on lemmygrad and more specifically GenZedong (actual ML's are welcome as long as they agree to the rules and don't just copy paste/larp about stuff from a hundred years ago).

The only dangerous minority is the rich.

We must constructively learn from their mistakes, while acknowledging their achievements and recognizing when they have strayed away from socialist principles.

(if you are reading the rules to apply for modding this community, mention "Mantic Minotaur" when answering question 2)

Notable achievements in all spheres of society were made by various socialist/people's/democratic republics around the world. Mistakes, however, were made as well: bureaucratic castes of parasitic elites - as well as reactionary cults of personality - were established, many things were mismanaged and prejudice and bigotry sometimes replaced internationalism and progressiveness.