"Tankie" is a derogatory term for Marxist-Leninists. We support AES or "actually existing socialist" states, in contrast to left idealists who support every revolution except the ones that actually succeed, which can always be imagined as perfect because they never had to confront practical reality. We're known for our opposition to war (except class war) and belief in multipolarity, which is the idea that one nation shouldn't be the lone superpower with hegemony around the world, and we treat the media with reasonable skepticism when it tries to tell us who to hate - ironically, these traits cause us to be characterized as militaristic, authoritarian, and blindly gullible.
People who have never read any communist theory beyond the Manifesto (if that) don't think we're real communists because they have no idea what they're talking about.