Don't Try This At Home
You know the Leidenfrost Effect. Oh yes you do, and no it isn't a new BBC radio comedy series. It's that thing that happens when a drop of liquid is in contact with a surface much hotter than its boiling point, and it floats on a layer of vapour. You have almost certainly seen it when somebody tests a skillet's temperature by dropping some water into it. Chemistry students love it because they can "accidentally" spill liquid air over novices' feet without any danger to the poor victim, who is however generally expecting her/his feet to freeze and shatter.
There are other party tricks which can be done with the Leidenfrost effect if you're not of a risk-averse disposition. For example, you can wet your finger (very thoroughly!) and dip it into molten lead, as in this Mythbusters programme:
Or you can take a mouthful of liquid nitrogen and (quickly) spray it out like a dragon's breath:
If you ever wondered what exactly would happen if you were incautious enough to swallow the liquid nitrogen when doing that trick, here's one we prepared earlier courtesy of Michael Mazur of the Worcester (MA) Polytechnic Institute. To quote Dr Paul Bankey of UMass Memorial Health Care:
"Physicians always say they learn a lot from their patients," says Bankey. "Michael's horrific chemical accident taught us once again that in trauma and emergency surgery, it's best to expect the unexpected."
You can probably guess some of his injuries, but I bet you don't guess them all. It really is an impressive testimony to the medical team that the guy isn't dead.