OK, here's one I finally broke myself of after several near misses.

It goes like this. You're on a quiet road and hear [and then see in your mirror] a car coming up behind. You ease just a little to the right if you've got the room and let them pass. THEN you ease back to the left, dropping kinda' into the car's wake. . .ONLY to find there was a second vehicle behind the first!!! D@mn!

As I say. . .I finally stopped that maneuver.