The 'I'm a sign not a cop' meme originates from a scene featuring the ever-insightful Lisa Simpson. This particular template showcases Lisa standing next to a sign in an alley that reads 'KEEP OUT' on the top and humorously follows with 'OR ENTER. I'M A SIGN, NOT A COP' below, effectively nullifying its own authority. The meme cleverly highlights the absurdity of rules and warnings that are self-aware of their lack of enforcement power, encapsulating the comedic brilliance often found in 'The Simpsons.'