My mind latched onto Reddit -> Twenty Year Olds -> Activists -> MLM
and then filled in MLM to mean Marxism-Leninism-Maoism, which has a decently sized base of twenty-year-olds on r/socialism.
In retrospect, it wasn't really the obvious choice for me to assume as for what MLM meant.
... I need to remember not to comment on stuff before I have coffee.