Busted

Adam's sister then slowly but purposefully placed her knee on his crotch and began to push, slowly increasing the pressure on his balls as she forces her knee up into his scrotum she leans in and whispers:

"Scream for me slut"

Adam resists at first and chooses simply to endure the pain of his sister grinding his balls against her knee, however his futile resistance is soon broken by his sister moving her knee back off of his balls then in a lightning quick move bringing her knee once more up to his crotch this time slamming it against his balls. This causes Adam to squeal in a high pitched rasp and he bends over trying to protect his privates more out of instinct than actual disobedience to her orders (he was far too much of a bitch to even consider conscious disobedience to his new mistress).

Upon seeing her brother doubled over in pain she smiles and takes the opportunity to move around behind him, then swipe his feet out from under him and push him face first into the ground. Adam recovers enough just in time to stop his face from slamming into the ground by bracing himself with his hands. His sister then lowers herself on-top of him and jams her cute, pert bottom onto the back of his head (this forces him onto his chest instead of his arms, making him immobile).

She then reaches forwards and grabs handfuls of his ass, roughly squeezing and molding the flesh with her hands, her sadistic streak then kicks in once more as she starts to use her nails in order to scratch Adam's naked **** flank. She then suddenly breaks this off with a powerful slap that causes a sharp clapping sound and also gets a sharp intake of air out of Adam. For several minutes she alternates between cruelly gouging his ass with her nails and viscously slapping his rear end. Finally after what seems like an eternity to Adam she climbs off Adam and returns to her suitcase of toys and proclaims:

"This you all nice and warmed up now it's time for the real fun to start"