This took me so long to get because the lid looks kinda like a stethoscope at first.

In mathematics and computer programming, the order of operations is a collection of conventions about which arithmetic operations to perform first in order to evaluate a given mathematical expression.

The order of operations is part of arithmetic. Although, the memes about it are certainly not good mathematics communication.

The annoying prevalence of this meme suggests to me that an alarming number of people lack even a middle-school understanding of basic arithmetic.