I don't. I think it is a huge PITA to be honest. If an oncoming car does it I spend the next 15 minutes looking out for things that probably aren't there and then when there is no police or anything I wonder WTF were they flashing me for? And I know of a person who flashed the oncoming car, who happened to be an unmarked police car and they were booked LOL. So it does make you think twice about doing it.

