Someone who dislikes everything and everyone and constantly voices his criticism of everything/everyone. This person is often angry with others for offending him in some way and his CONSTANT griping will mark him as a "hate-asaurus rex" rather than merely a "hater." Additionally, a hate-asaurus rex typically calls other people "haters" in an effort to disguise his "hater" comments.
Anthony: Stop being mean to me; you are such a hater! Why'd you change..you don't look good in shorts OR skirts! (...and this type of person would keep complaining...)