Spherical Cow

This mural makes fun of the fact that so many assumptions must be made in high school physics so that the problem is solvable. You will never actually find or need to calculate something about a spherical cow of uniform density! This idea is often referred to as the spherical chicken world, so there is also a spherical chicken below the cows.

The greek letter mu is pronounced a bit like moo, so the cow is saying it! It is most commonly used in physics problems as the coefficient of friction (higher coefficient means harder for something to slide).