Video: Alton Brown has been the world's preeminent food science wizard since the early days of the Food Network, and he's about to embark on his second tour. What better way to celebrate than with a big vat of ice cream? The Jet Cream is essentially three water cooler bottles duct taped together. On one end is a CO2 fire extinguisher, on the other there is a pressurised spray of liquid ice cream. In between, there are a few vent holes to prevent spontaneous explosions.
Brown explains that the ice cream mixture rushing towards an extremely cold gas in a (mostly) closed environment causes a Joule-Thomson effect. All you need to know about this is that the CO2 rushing into the water cooler jugs is about -100C, and because the ice cream mix is a spray, each of those tiny droplets is getting bombarded by all sides by really cold gas and freezing almost instantly. Bonus: The result is carbonated!
Does this work with other beverages? A jet-blasted frozen mojito sounds great right about now.