The Parrot's Theorem is a humorous and informal mathematical theorem that originated in a cartoon by mathematician and author Paul Erdős. The essence of the theorem is that if a parrot mimics the phrase "I am a math genius," then at least one person in the room will believe it. While not a formal theorem in the traditional sense, it serves to illustrate ideas about belief, perception, and the influence of authority or charisma in discussions, particularly in mathematics and academia.