Do you mean when you flashed your headlights to indicate 'go on mate, your turn'. In France flashing headlights means the opposite i.e. 'Get out of my way boyo'
it actually means the same in britain too.
Rule 110 of the highway code.
110
Flashing headlights. Only flash your headlights to let other road users know that you are there. Do not flash your headlights to convey any other message or intimidate other road users.