The Ice-Worm Cocktail

Step 2 Liquid #$%&*! nitrogen?

OK, so if you want to lay your hands on some of this, you should probably make friends with a science graduate student. They splash it around like water. You shouldn't; it's dangerous when handled incorrectly. Getting splashed with it is mostly harmless thanks to the Leidenfrost effect, but prolonged contact will result in a burn. You should respect any substance at 196 degrees below zero, especially one that is planning in the near future to get 700x bigger.
Storing it, fortunately, is easy. Get a stainless steel thermos flask, and pour in your cryogen. Most of it will keep overnight, more than enough time for your party. Don't screw the cap on though, because in doing so you will have made a bomb - just stuff some tissue in the top. The liquid nitrogen will slowly boil off. I despise glass-lined dewars, as they're prone to imploding (which trust me, is entirely indistinguishable from exploding), and you'll be picking bits of glass out of your face for weeks. 
Eric makes some good safety exhortations regarding the handling of this substance while making ultra-cold cocktails. You should listen to him.