From Longman Dictionary of Contemporary Englishflip somebody ↔ off phrasal verb American English informalRUDE/IMPOLITE (also flip somebody the bird) to make a rude sign at someone by lifting up your middle finger and keeping your other fingers down → flip→ See Verb table
Examples from the Corpus
flip off• I flipped the machine off and stared at it.• I shake my head at the pill, and he flips it off the bed like it was a bug pestering him.• The goats lunge at each other with their horns and try to flip each other off the ledge.• Depending upon whether that bit was flipped on or off, the pixel on the screen would be dark or light.• Sam flipped it off, turned the log, measured again, and cut off another slab and another Fitch. 