(My living group is doing Rush right now, which means my life is basically eaten for the next two weeks, such that I feel no shame about writing a punt-tastic post like this.)
I will just note that $18 can buy more dry ice than twenty MIT students can play around with for three hours. Try it out some time. Make sure to bring soapy water, interestingly-shaped glass vessels, small white and colored lights/LEDs, coins, spoons, and hot water.
Try putting a little water in a spoon and then resting the spoon on top of a chunk of dry ice. You can see the water freeze right before your eyes. It's pretty cool.