snook \SNOOK\ (noun) - 1 : A gesture of defiance and/or derision. 2 : Any of several kinds of salt-water fish of family Centropomidae, such as the sergeant-fish and the robalo.
"Sarah's rendition of 'I'm still standing' at the karaoke evening was a transparent snook aimed at the management cabal trying to force her resignation."
No-one knows where the gesture got its name. There's a possibility that "snook" may have been the origin of "snooker," British military slang for a newly joined cadet (who might have been cheeky enough to cock a snook at a passing officer's back). The cadets, in turn, may have been the origin of the game of pocket billiards now called "snooker," but originally named "snooker's pool." But both connections are built more on plausibility than evidence.