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One who is a two faced, backstabbing, freak. This is also used for dogs and children with hyperactivity disorders.
Mary, you are a friggin' flip case.
Jose! RUN! There is a flip case running toward you.
Marlene over there is a flip case.
by Fly-J May 28, 2007
A person who, while seeming normal, could "flip" in an instant to become their darker self. You can usually spot their intensity, boiling just below the surface.
Different from nutcase who always shows their lesser self.
"You know he's a flipcase so watch what you say."
by JohnCanon March 30, 2010