Prompted by the question: " How did kool-aid come to be the drink of fanboys? "
Wikipedia's explanation on "Fanboy (disambiguation)" provides:
A fanboy is a person considered to belong to one or more fandoms to a point of obsession.
(fandom slang) Someone (normally male) who is utterly devoted to a single subject or hobby, often to the point where it is considered an obsession.
While the general term "fan" derives from "fanatic", its current usage, in the US at least, has waned to be roughly synonymous with "admirer" or "someone who is fond of --."
Are the terms "fanboy" and "fangirl" gender-specific synonyms of "fan" or are they supposed to convey the same "fanatic" intensity that "fan" once had? Are "fanboy" and "fangirl" intended to be used in a derisive way?