thumb nose at behind his/her back(Секретарша показала своему начальнику кукиш в кармане. The secretary thumbed her nose at her boss behind his back.; выразить трусливое, робкое несогласие to express disagreement or rejection in a cowardly manner (in Russian literally "to show 'a fig' in one's pocket," a fig being a rude gesture in the form of a fist with the thumb protruding between the index and middle fingers))
