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The reappropriation of the word "queer" from a pejorative term to a term of self-identity and strength for the gay community has been well documented. It's worth pointing out though that another symbol currently associated with the gay rights movement, a pink triangle, is itself reappropriated from its much more menacing origins in Nazi identification systems. The pink triangle was, like the more well-known yellow Star of David, used to mark a population the Nazis deemed threatening, in this case homosexual men. Trusty Wikipedia has a brief discussion of the phenomenon with lots of relevant links.