Spitegender is a xenogender that exists out of pure spite of those who don't believe xenogenders, or non-binary genders in general, exist. It can also be defined as a gender that feels somewhat spiteful in nature.
History
This term was coined on August 20th, 2021 by Twitter user @CloudyMoth on this post to spite an anti-xenogender user. The three flags were also made in the same post.
Source
https://mobile.twitter.com/CloudyMoth/status/1428865589553025029?lang=en