Science!
In third year Biochem, I was busily freezing RNA samples in liquid nitrogen, when I decided that it would be in the interests of science if I tested how cold liquid nitrogen is by taking the pair of tongs that had been sitting in it and putting them on my arm.

It turns out that the temperature of liquid nitrogen is about −196°C, which was more than sufficient to freeze the skin on my arm solid, and leave a nasty burn when it thawed out.

I managed to follow this up a couple of years later when I tried to recap a syringe of ethidium bromide, and instead of placing the needle into the plastic cap, I plunged it into my knuckle. Thus far the finger has not mutated into a catchphrase-spouting amphibious ninja, so hopefully I'm clear on that front.
(oball needs Satan more than he needs me, Wed 2 Jan 2008, 2:27, Reply)