Quote: "I don't want to talk to you no more, you empty headed animal food trough wiper. I fart in your general direction." French solder in Monty Python and the Holy Grail
Figure of Speech: mycterismus (mick terr IZ muss), the sneer
A mycterismus (from the Greek "to sneer") mocks someone through voice and gesture. When one breaks wind rhetorically, it counts as a gesture, and maybe even a voice.
These days a mycterismus means yelling a profanity while redundantly flipping the bird. The French soldier played by John Cleese in the Monty Python movie makes a more atmospheric gesture.
Snappy Answer: "That's the smartest thing out of you yet."