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A term that originated on Facebook, Chapman's Law states that as an online argument grows longer and more heated, it becomes increasingly likely that somebody will question if a photo of someone is displaying their cumface. When such an event occurs, the person guilty of invoking Chapman's Law has effectively forfieted the argument.
"What a mentalist. All that with her kid in her arms!!"

"That Daily Mail pic is probably her cumface."

"Ah, so it's time to invoke Chapman's Law, is it?"
by TheMightyPrune November 29, 2011