In Australian slang, someone who is the opposite of a "mate" (a friend or companion) is often referred to as a "bloody drongo" or simply a "drongo." The term "drongo" is used humorously to describe someone who is foolish, incompetent, or not very clever. It's a light-hearted way of poking fun at someone's lack of common sense or abilities. Keep in mind that Australian slang can be playful and context-dependent, so the term might be used in a teasing or affectionate manner among friends.