snap (one's) fingers at (someone or something)
1. Literally, to perform a rude gesture in which one touches their nose with their thumb in order to express contempt or a lack of respect. Did that guy really just thumb his fingers at me? Do people still do that?
2. To display open contempt or an intentional lack of respect toward someone or something. Don't thumb your fingers at the boss if you want to keep your job!
snap one's fingers at
Treat with contempt, scorn, disregard, as in Peter just snapped his fingers at the speed limit and drove as fast he liked, or Joanne snapped her fingers at the rumor about their bankruptcy. This expression alludes to the gesture of striking one's finger against one's thumb, thereby making a sharp noise. [Early 1800s]