This exact thing happened to me a few years ago, but I was really sick at the time so I thought I imagined it. I had the flu, and I found this water bottle int the back of our freezer, which was conveniently unfrozen, so I grabbed it and shuffled over to the couch, and when I opened the bottle it was solid ice. I MUST repeat this...

Actualy its like this
It is "superfreezing" persay but the bottle must have been standing strait up and must have been REALLY FREAKING COLD in order for this to happen
i found this as well

That is in fact the supercooling process but there are absolutely no restrictions other than it has to be colder than freezing and nucleation must be suppressed. In fact The Argent Lord commented that the bottle was under other bottles most likely indicating the bottles where on their side. Though the colder and slower you freeze the water the greater chance you'll get supercooling.

i just read somewhere that it doesn't matter as long as you don't agitate it so i was wrong there but yes i just looked up supercooling...interesting stuff would be a fun experiment later

You know, deep down, im really disapointed at all of you.. with all you "science" and "facts" and "logic" not one of you were kind enough to actually consider the possibility of Argent Lord having developed superhuman freezing powers... FO'SHAME

It's really easy to do with carbonated drinks, which stay liquid slightly below 0°C. Then when you open them usually some of the gas escapes and voila.