Non-newtonian fluid is a substance that doesn’t quite act like a liquid or a solid. If you stand on top of it you will sink but you can run across it.
Wiki: The application of force — for example by stabbing the surface with a finger, or rapidly inverting the container holding it — leads to the fluid behaving like a solid rather than a liquid. This is the “shear thickening” property of this non-Newtonian fluid. More gentle treatment, such as slowly inserting a spoon, will leave it in its liquid state. Trying to jerk the spoon back out again, however, will trigger the return of the temporary solid state. A person moving quickly and applying sufficient force with their feet can literally walk across such a liquid.
A bit hard to understand without visual aid:
An example of non-newtonian fluid is quicksand. Quicksand, when undisturbed it often appears solid , but a minor (less than 1%) change in the stress on the quicksand will cause a sudden decrease in its resistance inside the fluid. So if you step in it you will sink and if you to remove a foot from quicksand at a speed of one centimeter per second the force require would be the same amount of force as “that needed to lift a medium-sized car.”
Now you might ask, how do I create this crazy fluid? Well, do not fret, youtube has the answer. Only need cornstarch which you can find in any shop and normal water.
Isn’t science awesome??