What is Binary System?
Originally used by computers to store information (using only 0's and 1's) (see above), this two digit system has been co-opted (often, but not exclusively, by men) and used as a tool to assess others' appearance (often, but not exclusively females').
The "binary" procedure of assigning a numeric value to someone's appearance assumes that one thing, and one thing alone matters: whether or not the assessor would have sexual intercourse with the person being assessed. Thus, "1" implies that the ranker would, given the opportunity, indeed have sex with the person in question while "0" implies that he/she would not.
Many practitioners of this system claim that it is the most honest measurement of someone's attractiveness, because its measurements are completely straightforward--there is no in-between. Fractions are implicitly forbidden in the binary system, and even hesitant tones and vocal slants are frowned upon during the ranking process, as they undermine the absolute nature of the system.
One might call into question the veracity of the system based on the differing moral standards and social norms of its varied practitioners, but that is, I believe, beyond the scope of this definition.
example of two acquaintances discussing a friend's new girlfriend using the binary system:
Jim: "Yuck, Biff's new girlfriend is definitely a 0"
Skip: "Well then Jim, I guess it's good that Biff, not you, is dating her"