Guy factor is acquired experience gained from doing male type activities. This can include but not limited to: dating, hooking up with females, use of slang or cursive language, ability to pick up females, high pain tolerance, high fear tolerance. Guy factor is measured in Yx, where "Y" represents the number of experience gained and "x" represents the factor, just like in a mathematical equation or representation of an unknown number or factor.
Bill: "Yo, did you see Chad hook up with Cattie?"
Robert: "Yeah man, his guy factor increased from 15x to 16x man"
Bill: "Yo, did you see Chad cry while watching that chick flick?"
Robert: "Yeah man, what a pussy. His guy factor went down 2 steps for crying and watching a chick flick. 16x to 14x."