A mathematical law, regarding dance records. "The product of R and C is inversed proportionally to A." where R is the rarability of the record, C is the credibility in playing the record, and A is the availability of the record. This means that finding a cool record to play that your cool DJ pals will respect you for playing, is utterly impossible. See also Greiff's Law of Credibility and Murphy's Laws of Dancefloor Content.