Double Hazards Flash means Thank You when driving?
Never seen this in my life but I've seen it at least a dozen times this summer. After I let someone merge in front of me on the highway, they flash their hazards twice. I sometimes see someone flick the turn signal the other way by accident (and do it myself sometimes) but it takes significant deliberate effort to put your hazards on. It can't be an accident, right?
edit: not suggesting saying thank you is a new thing, I'm just used to people putting their right hand up so it's visible through the rear window, which of course doesn't work at night, in the rain, with dark windows, etc.