Hey, if they aren’t using Waze, there isn’t much I can do to help them.
I love option three! ‘Bah, it’s an Audi, let them get clocked.’
There is a theory that in the UK, if Plod catches you flashing other motorists you will get done for “obstruction” or some such. 5 to 10 stretch in chokey. Well, three points on your licence and a hundred quid fine anyhow.
Pervert.
So did I.
As with many things, it depends.
First, I would never do it at night.
There is a section of road that I drive every day that has a ridiculously low speed limit. 35 mph on a two lane highway. The police seem to love it. I’ll warn people in that case.
There is an area near my house that I drive every day (twice actually). The speed limit is 35 most of the way, then for a short distance it’s 25 mph. There are often cops there with speed guns. People flash their headlights and warn each other. I’ve been trying to figure out who to write to to request a uniform 35 mph on that road. 25 mph on this road is insane. On a highway with a 65 mph speed limit, everyone is on their own, as far as I’m concerned.
It’s easy for me to imagine you throwing a string of beads to every driver who tries to warn you of danger ahead. hehehe 
Well, now you know one of the 10,000 reasons they might be doing it. When someone does it to me, I always wonder if they were warning me or just being a jerk to the people in front of them. Though, I was surprised to learn in my 20’s that everyone didn’t think someone flashing their lights was to warn oncoming motorists of Kojak with a Kodak. My dad had taught it to me when I was a kid, and I thought everyone knew.
I have been known to warn oncoming drivers by flashing my lights before. But, I’ve also been known to egg someone who’s been tailgating me into a quick race, then quickly slow down and dump them as they shoot over the hill and see the cop that my radar detector has been complaining about for nearly a mile*. So, on top of them nabbing me, I’ve fed a few unsuspecting victims to them as well. On balance, it’s probably a wash.
*Don’t tailgate Subarus with radar detectors while you’re both already traveling at a ticket-able speed, and this won’t happen to you.
ETA: And yeah, I thought of Mardi Gras upon reading the title of the thread.
If someone flashed me, I would assume they were trying to tell me my headlights were not on or my high beams were on. Or, if we were on a rural road, I would assume they were trying to turn their high beams off and accidentally turned them on.
I’m not familiar with flashing to warn of speed traps.
I haven’t gotten caught in a speed trap since I started using Waze, but yes I would flash my high beams to warn others.
Fuck them, they deserve to get caught, whey would I enable their breaking the law?
Did it once when I was a teenager, flashed an unmarked police car…got chased…learned lesson.
And then there was the time previous to that when myself and my friends thought it would be a great idea to set up our own check-point on an isolated country road using a torch and red cloth.
First car we waved down was again an unmarked police car. I think somebody’s trying to tell me something.
I wouldn’t, because it never occurred to me that someone flashing theirs at me would be a warning about a speed trap.
I learned only one thing about high beams; turn them on when you are about to crest a hill on an undivided road - otherwise, your headlights shine directly into the eyes of oncoming traffic.
Speaking of high beams, is there a legitimate reason to ever use them other than for “flashing” purposes?
Dark country roads. They help to see animals running across the road, which the little fuckers invariably do when a car is going by. Now you may not care about a squirrel or a chipmunk (I do) but I don’t want to hit a large sized turtle or even a deer.
I flash my high beams all of the time, in the context of telling an overtaking driver that they have room in front of me to merge. Or that the car pulling out of the parking spot, or the pedestrian paused in the intersection, should advance and I’ll wait. It’s a shorthand for, “Go Ahead.”
Flashing to warn someone of a speed trap? No. I will flick though my lights on and off if the oncoming driver has forgotten to turn theirs on. (It never works.) In the well-lit city, and with modern cars, it happens a lot more than you’d think.
I’m sorry to have mirth at your misfortune, but that’s funny as hell. Like speeding, if you engage in breaking the law, you pays your nickel and you takes your chances. If a cop sees you flashing your high beams, they’re going to be either confused or very interested.
(bolding mine)
I think you mean off, when they are already on. When crossing the arc of a hill simultaneously, your headlights will shine into the eyes of the oncoming driver at some point. The focused beam of high beams is going to be more blinding than the diffused low beams.
Yes, if you are on an unlighted road without oncoming traffic, they are very useful at seeing far ahead. I’ve missed several skunks because I was using my brights. If missing a skunk isn’t a valid reason, I don’t know what is.
I have heard people recommend that you turn on your brights if you weren’t otherwise using them when rounding a bend on an unlighted road to inform oncoming traffic that you’re there, but I don’t really agree. ISTM that the wider spread of low beams would be more noticeable to an oncoming car around a hedged turn than the focused light of high beams.
I’ve seen this discussed here before. I do not, however, think warning other drivers of an upcoming radar gun is illegal in the US.
The scenario is less useful in practicality at night. If someone flashes their high beams to me at night, my first assumption is that I have absent mindedly left my high beams on and they are trying to signal to me that I should put them on low. In the daytime, I would first assume that there is a speed trap ahead.
Oh no worries, I laugh about it now, but it certainly wasn’t funny at the time! Especially as when I was being chased* by the police car, I turned off onto a sidelane that I remembered as being a short-cut, unfortunately at some point it had been blocked off and was a dead-end, luckily they didn’t spot me turning off and drove past. But as I said, lesson learned!
*not quite accurate, I saw them turn to come after me and hid almost straight away
Its a grey area in the UK as well, I can’t recall the legislation accurately but I believe its only an offense if you flash your lights to warn a vehicle that is speeding. Yes, I have no idea how you would or could prove that.
There’s (naturally) a Wikipedia entry about headlight flashing.
It talks about the legality and illegality in various jurisdictions.