It's called a whipped cream syphon, and it works on the same principle as a seltzer bottle.
You put very cold whipping cream in one, put the top on, and attach a cartridge of nitrous oxide. The nitrous oxide dissolves in the cream the same way carbon dioxide dissolves into water to make carbonated water.
When the cream squirts out, the dissolved nitrous oxide effervesces and makes the cream whip.
As an aside...the nitrous cartridges are available in grocery stores with gourmet sections.
And yeah, it's that kind of nitrous oxide
Gives great pumps though, NOXplode. I guess she forgot the exploding part