When boning a girl, and at the same time constantly flirting with her roommate, to the point where the original "bonee" freaks out on you for these obvious flirtations, leaving you and the roommate alone together in a bar. Being a gentleman, you makes a half-hearted attempt to get the "bonee" to stay, but when said attempt fails, return to the bar to continue flirting with the roommate. After consuming mass amounts of alcohol, you and the roommate return to her shared domicile and consummate your flirtations while the original "bonee" is passed out on the couch. Essentially, completing the roommate fuck switch without having to come up with any elaborate stories to get the original "bonee" off your nuts.

This technique is believed to have Brazilian roots, and later migrated to the US.
Person 1: Hey yo, did you hear what Ken did last weekend at the bar?
Person 2: No, what?
Person 1: He pulled the KC Switch on his girl and her roommate!
Person 2: Damn, that dude is so playa!
by Larry Sanders Has a Posse August 17, 2009
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