I went and got a coke from the fridge, and I pop it open, and go to take a sip, and the ENTIRE coke is frozen, I even cut the can in half, and both sides were ice. How the hell did that happen?!
The chemical answer is, when your coke is really cold, and you open it up in room-temperature/warm environment, the rapid exchange of cold/warm air is very quick. The air that shoots out of the coke will cause the insides to freeze very quickly. It's actually pretty cool, but I never had it happen to me myself.
It's called having sensitive teeth. Can't really be helped without a visit to the dentist or special toothpastes and whatnot. Has to do with the enamel.
I used to have sensitive teeth. Not anymore, though.