Non-Newtonian fluids are seriously strange — a mixture that takes on properties of both a fluid and a solid. Watch as people perform a number of physics-defying tricks on a 2,100 galloon pool of "oobleck."
The viscosity of non-Newtonian fluids change according to the amount of force applied to it and include everyday items like ketchup, toothpaste, shampoo, paint — even blood.
Oobleck is basically a mixture of corn starch and water. You can even make a batch yourself; check out this video in which the HardScience team tries to bike across a trough filled with home-made oobleck:
[h/t Laughing Squid]