That reminds me of a similar story about double positives that I can never remember the details of. Fortunately wikipedia came to the rescue:
"During a lecture the Oxford linguistic philosopher J. L. Austin made the claim that although a double negative in English implies a positive meaning, there is no language in which a double positive implies a negative. To which Morgenbesser responded in a dismissive tone, "Yeah, yeah." [1]
A news editor prints a story about the adage, with the headline: Betteridge's Law of Headlines, is it true?