First we must know what a non-Newtonian compound is. Something that is non-Newtonian is a substance that does not follow Newton's laws of viscosity. These kinds of substances only change with pressure of temperature and are thus called "normal liquids/fluids".
However, some liquids don't only change with the temperature and pressure, and these are known as non-Newtonian compounds.
Some examples of non-Newtonian compounds are ketchup (because it gets more liquid-y as you shake it---hence why you shake a ketchup bottle before opening it), honey (the liquid is always very unmoving and is ONLY dependent on temperature---if you heat it up it becomes more liquid-y).
