Oobleck, a common name for the final product of mixing corn starch with water. Not only is it named after the mysterious materials falling from the sky in the Dr Seus's story, "Bartholomew & the Oobleck," this combination of materials is a great example of non-Newtonian fluid. (What is a non-Newtonian Fluid? What is Newtonian?)
How does it depict a non-Newtonian fluid? Standalone, Oobleck appears to have liquid behavior. However, when applied pressure, force, or punched, the Oobleck hardens. This is a clear example of shear thickening caused by application of pressure and another example of how important shear thickening behavior can be analyzed for real life applications!
Watch the National Institute of Standards & Technology (NIST) DIY their own Oobleck and explain the reactions in detail: