Smack her balls

"Crawl after me." You say, poiting to your feet. Your futa slut crawls after you as you walk down the hallway, swaying her hips side to side and making her cock bump against her thighs as she does.

Once you´re in your bedroom you fetch a set of simple leather cuffs and, after removing her shorts and shoes, you help her up and cuff her hands behind her back. You then attatch a short leash to them and tie it to one of the legs under your bed. Holding her close and kissing her, you fondle her large balls. "So, you like it when I´m mean?" She smiles. "Yes IAAAH!" She screams as you squeeze her balls hard. She tries to bend over, but you hold her up and keep your hard grip on her balls. "Well then, I guess I´ll just keep being mean then." you grin, letting go of her balls for a few seconds, only to smack them hard, letting her fall to the floor huddled up in a futile attempt to protect her balls.

With her arms cuffed behind her and pain pulsating in her crotch, she can´t do much to resist you as you pull her over, placing her on her back and putting your foot on her shaft, pressing it against her stomach. As you move your foor further down, towards her balls, she whimpers. "Please, pleasnodonuaaaagh!" She scream at your quick stomp.
Again, you place a foot on her shaft, enjoying the tears running down her cheeks and her pleading eyes. "What are you?" You ask in a mocking tone. She shouts back. "I´m your slut Master! I´m yours! I belong to you!" You grin. "And can a Master do whatever he can with his property?" She sniffs, trying to clear her nose. "Y-yes Master."

"So, as your Master it is up to me what happens to your balls, not you." Again, she whimpers. "Yes." "So, present your balls to me Slut. I want to see them." She moves her legs and hip thrusts her crotch up, letting her balls dangle enticingly between her legs. You pull your leg back, readying a soccer kick. "What are you going to do now Slut?" She whispers, just loud enough for you to barely hear. "Stay still and let you hit my balls Master."
You smile. "Correct." And with that you kick her hard in the balls, making her scream loudly. However, despite the pain you see she tries her damdest to maintain her hip thrust position. She grits her teeth and you hear her breathing rapidly. With shaky legs she pushes her hips back up, presenting her balls to you.