A person of Greek descent or a self hating Agean Macedonian who denies the existence of a certain ethnicity and will go by all means necessary (This includes assimilation, indoctrination, and oppression) to destroy that identity and Greekify it. A typical example is a Greek denying the existence of a separate, non-Greek nation called Macedonia with Macedonians being its majority population. The Greek then continues to deny the existence, despite the fact that his claims are refuted over and over again to the point of absurdity.
There are way too many greekclowns in my neighborhood. All they try to do is convince me how Macedonia is actually Greek and how Alexander was Greek. Don't they have anything more productive to do in life?