Come up with a punishment

"My my, you really cut it close there didn't you Katherine," you say, "But you did survive. So I officially award you another point which puts you in the lead with three points. Given my dick has been sufficiently pleasured for the moment by you and your lovely, but losing, sisters, I declare you the winner of this morning's cum competition."

Katherine is still lying flat on the floor, reveling in her orgasmic bliss but she tilts her head up to look at you, a smile crossing her face at her victory. How petty a little competition has made these girls. Or maybe its fear of punishment. Speaking of which, you haven't quite decided what the punishment for Emma and Sabrina should be.

Sabrina is still gagged and tied on the carpet, having watched the whole fuck machine scene and your multiple orgasms with Katherine and Emma, unable to speak or move. Emma meanwhile is also tied up and gagged, by Katherine's hands. Both however are looking at you now, beautiful but wary eyes watching as you think.

"I wonder, Katherine do you have any thoughts on a punishment for your sisters? You know both of them much better than I do," you ask.

Katherine looks at you and then at her bound sisters. She's quiet for a moment and then beckons you to come closer.

You move over towards Katherine and lean over. She whispers into your ear, "We used to fight all the time, you know over petty stuff or boys or whatever. I think maybe you could have them fight it in one more round out as initial punishment, with an even worse punishment for the loser."

"Interesting idea, I like it," you say.

"Alright Emma and Sabrina," you say, moving back over to the other two girls, "As your initial punishment, you will have to fight against each other. The loser will suffer an additional round of punishment that the winner will decide, with my approval of course. I will untie both of you and place one vibrator between you. You can use this vibrator or your hands, mouth, whatever you see fit. The first to make the other orgasm wins. You may use your body to get an edge using whatever means you desire, but only your body. Further, you will be covered in lube to make it more difficult to subject the other, and you may not cause any significant harm. Got it?"

Sabrina and Emma look at you in shock but both nod their heads after a brief pause. Then they look at each other and their gazes harden as they prepare themselves for the fight. You grab a bottle of baby oil and a few spare towels. You lie the towels side by side to form a small wrestling mat and haul the girls over it. Soon the bottle of baby oil is being poured on Sabrina and Emma until it is empty and they are completely covered in the slippery stuff. Its finally time to untie the two girls and although you're worried they may try to escape, you're fairly certain you and Katherine can handle the two of them.