Thumb One's Nose Meaning

(figuratively) To act disrespectfully, especially by flouting the object of disrespect.

Example: To place a thumb upon the tip of the nose, typically with the fingers spread and while simultaneously wiggling one's fingers, in a gesture of disrespect.
  My brother thumbed his nose in reply to my snide remarks.
  Richard Feynman delighted in thumbing his nose at bureaucracy.