Circular Reference

In Excel, a circular reference is when a cell references itself; ultimately, a massive flaw in logic.

Someone who is the human form of a circular reference is someone who displays a massive flaw in logic. I.e. someone who is Derp, is also a 'Circular Reference'. They have zero logic to anything they do.

In the workplace -

Person A: Hey, did you hear that Sue wrote over all our templates?
Person B: Sue is basically a circular reference.

In life -

Self explanatory. We all know that person who is a circular reference. 9/10 they are named Bryce.