Liquid nitrogen is an invaluable tool for scientists, and can make for some pretty awesome experiments, but introducing it into a pool party? What the hell where they thinking? As you can see from the video, it got ugly pretty damn quickly.
Apparently the organisers of a Jägermeister pool party in Mexico thought it'd be an amazing idea to dump four buckets of liquid nitrogen into the swimming pool while people were swimming. The idea was that it would create a smoke effect on the surface of the water, which it did, a little too successfully.
You see, liquid nitrogen boils at -196C, which means when it hits pretty much anything it boils instantaneously. That's what gives it its amazing dry-freezing properties, but what people don't realise is that as the liquid nitrogen reverts to its natural Earthly state it rapidly expands, filling the air with pure nitrogen gas. Seeing as we need to constantly fill our lungs with oxygen, sitting in an atmosphere of pure nitrogen is a really, really bad idea.
Essentially, the poor swimmers were almost instantly suffocated, causing people in the pool to fall unconscious, with one 21-year-old sent into a coma. The Mexican authorities are currently investigating to see if criminal charges should be brought against the organisers.
Liquid nitrogen is incredibly cool and all, but it's also potentially absolutely lethal. If it doesn't snap freeze bits of you, it can choke you to death with pure nitrogen gas. So, folks, don't mess with LN2 unless you know what you're doing. [YouTube via Geekosystem via io9]