Grover's law, an analogue of Godwin's law, states that whenever one Internet user accuses another of being a "sock puppet" (i.e. fake identity) without proof, the argument is over and the accuser has lost the argument.
The name of the law comes from a diagnosed paranoiac's belief that all Internet posts originated from the Sesame Street persona Grover.
UglyTroglodyte: "I suspect you are an alias of a resurrected, bionic Hitler."
Rx521: "Wrong! I invoke Godwin's and Grover's law! You lose double!"