3. Non-Newtonian Fluid
https://www.youtube.com/watch?v=RkLn2gR7SyE A non-Newtonian fluid is a material that doesn't follow the usual rules of fluid dynamics. The viscosity (its "thickness" if you like) will change depending on how much stress you put it under. "Oobleck" (the fluid used in this video) will "tense up" under stress (don't we all?) making it behave like a solid and causing it to dance wildly across the speaker surface. This is what most people picture when they think of non-Newtonian fluids (like you do), but there are also loads of examples of the stuff in everyday life such as ketchup - which actually gets thinner under stress - and semen which will, er, bounce if the conditions are just right.