The theory that the shorter the first name the greater the likelihood that person has a mustache. Only holds true for White Males that live in the United States.
Theory in mathematical terms:
Name<= 4 letters = Mustache
Name>= 5 letters = No Mustache
Stranger to gentleman with finely combed mustache: "Hello fine sir, may I trouble you for your name?"
Mustached Gentlemen: "Why yes, it is Al"
Stranger: "Mustache Theory!"