I had one a few days ago - I was driving home, when an ambulance came up behind me - lights, sirens, the full works. Of course I pulled over to let it pass, as did the cars in front of and behind me, except one guy who decided to use the opportunity to overtake a bunch of people, by barrelling along behind the ambulance. There's no way he couldn't see the row of cars all pulling back into the traffic.. I suppose we should be grateful he at least gave way to the ambulance itself.
I saw another at the weekend - 2 lane road narrowing to one lane, lots of warning, bug sign telling people to merge in turn (with diagrams showing what they meant) Everyone was taking turns except one guy who decided to pull out of him lane, drive all the way to the front and push in, rather than take turns like everyone else. (Happily for everyone but him, the entire queue noticed, and tightened up a bit. He was let in by the person ahead of me, who had been 2 cars behind him when he pulled out to queue jump :-)