Like in the car commercials for Carfax where it has the information on the car like how many owners wrecks and problems. Muff Fax is the info on a girls muff and how many "owners'' or problems like std's or anything undesirable.
Alex: I wonder how many guys she has been with?

John: We need to get some Muff Fax!
by 748134 August 31, 2011
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