Oobleck

"Watch what happens when force is applied to amazing and mind bending Non-Newtonian Liquid and filmed in slow motion."

What is it?
Oobleck

"An inexpensive, non-toxic example of a non-Newtonian fluid is a suspension of starch (e.g. cornstarch) in water, sometimes called “oobleck” or “ooze” (1 part of water to 1.5–2 parts of corn starch]. [8][9] Uncooked imitation custard, a suspension of primarily cornflour, has the same properties. The name “oobleck” is derived from the Dr. Seuss book Bartholomew and the Oobleck.”

http://en.wikipedia.org/wiki/Non-Newtonian_fluid