(Uncommon): Some bored, computer addicted Aryan who read a 2 paragraph definition of communism, and now wants the whole world to convert to it, by saying "Peace, justice, and freedom" on the internet. An example are Liberals or Democrats.
(Common): Some 13-25 year old dude who saw a video of a parade from the Soviet Union on youtube, and now goes to school wearing a Che Shirt. Such as Sam Webb or Andres.
The concept of communism, just like the concept of democracy, would work fine if it was not corrupt, or if it did what it claimed is stood for.