Cheeky LingoThe words they skip in class.

French phrase

T'es complètement fou / T'es complètement folle !

teh kohm-pleht-MAHN FOO / teh kohm-pleht-MAHN FOL

Literally
You are completely mad!
Means
You're completely mad! (finger twisting at the temple; -fou to a man, -folle to a woman)
everywhere in France (and understood across the French-speaking world)