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the act of clenching ur hand into a fist, then with the knuckles pointing at the vagina rub the knuckles up and down against it, the ridges beetween the knuckles make 4 maximum pleasure
person1: howd it go wiv emma
person2: a gave her a good knuckle thruster she was screaming!!
person1: nice one :)
by DJ SPYKERZ(SCOUSED OUT) July 31, 2009
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