Literally, 'Go do / make yourself.' One of the most vulgar forms of dismissal in the French language. To execute the gesture, make a fist with the right hand, and extend the arm out straight, parallel to the ground, fingers up. With the left hand open, slap the right bicep just above the elbow while raising the right forearm upwards to 90 degrees. Known as the 'Bras d'honneur.'
Roughly equivalent to fuck off, go fuck yourself, up yours, etc.
While stopped at a red light, the person behind you honks their horn for you to move. You give them the Bras d'honneur, and shout through the open window, 'Va te faire foutre, putain d'espèce d'enculé