She dances around in a bra & panties, bodysuits and in nothing but police tape, but that wasn't Lady Gaga in a brown wig in her new video for "Telephone" ... it was her kid sister.
According to Buzzfeed.com, Gaga's Amy Fisher-looking doppelganger is her 17-year-old sister Natali Germanotta.
Move over Ke$ha, Natali is the real baby Gaga!
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