Costcop

A costcop is a Costco worker who stands at the exit and verifies that a customer's receipt matches the items in their cart. Since the costcop enforces the door, they are compared to cops, but don't perform any similar functions.

It's unclear who coined the term, but it was most likely a disgruntled customer annoyed they had to wait in line to leave the building. While it is a minor inconvenience, sometimes costcops draw smiley faces on the back of the receipt, which totes makes the waiting worth it.