What not to do with dry ice

I found out that using dry ice to quickly cool down cans of diet pepsi is not a good idea. Oh sure, you say, "Well yeah", but it didn't seem like that bad of an idea at the time. The weirdest thing is the noises it makes when you put the warm can into the dry ice. It's mildly disturbing. If you ever saw the movie The Princess Bride, it was reminiscent of the shrieking eels. Freaky. So I leave the cans in there for 10 minutes, doesn't seem that cold. Another ten minutes, now the cans are hard as a rock. I'm thinking this can only end in tragedy. So my coworker decides to open one. Three quarters of the can rockets out of the can, leaving the remaining 1/4th frozen solid in the bottom of the can. One hour later, still frozen solid. The experiment a failure, I decide to stick to traditional methods for beverage cooling. Next weeks lesson: natural gas, if it's natural, can it be that dangerous?