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1.
Cheating or trying to cheat when you have a spouse or significant other. Those looking for sex on the sly are liars and cheaters.
Nancy: Did you hear? Monty's lookin' for some sex on the sly. Jack saw him hit on a girl at the club.

Alice: You mean Monty, Sally's husband?!

Nancy: Yeah, can you believe it? He seemed so sweet and caring to her. Go figure.

Alice: Uh huh, another cheater.
by mad megawoman August 06, 2011
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