The story
Variant of bizarre, equivalent to bizarre + -o; see that entry for more information. In the sense of “logical inverse”, derived via the comic book character Bizarro, an inverted version of Superman from a planet where “good” means “bad” and so on, and further popularized by "The Bizarro Jerry", a 1996 episode of the sitcom Seinfeld.
Etymology from Wiktionary, CC BY-SA 4.0.