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Holding a cactus plant or part of a cactus that resembles a penis close or up to the pelvis while clothed and moving the pelvis area like you are humping a person and/or an object. Another succesful way to cactus fuck is to move your hand around but not touching any part of the cactus in the motion of masturbating
Cactus Fucker- Haha Look. What does this look like?

Friend- Eew stop cactus fucking!
by Kameroon June 20, 2009