Wiktionary
vb. (context UK idiomatic pejorative as a gesture English) To perform a snook, a gesture of disrespect.
Usage examples of "cock a snook".
The nations of Earth, the whole fat Federation, they need somebody in a position to cock a snook at them.
He imagines himself as a traveller, being able to cock a snook at Dr Hodgkinson and sharing a coach with Sally and Sammy.
Even cautious pupils like himself were swept along by a desire to cock a snook at authority.
So unless the document is actually handed over, Lothar will be able to cock a snook at us, walk off, and plan a further attempt to get hold of it which we may not be fortunate enough to find out about.
But as long as the aristocracy still cuddles up to the Empress, long may she reign, they can afford to cock a snook at the Church.
So that you could cock a snook at the arrogant male, the Victorian paterfamilias?