Tackle her

You don't even bother getting to your feet. You throw yourself forward and pin your sister down.

A wild exchange begins and you and your sister are savagely kneeing each others nethers. You slam your knee down hard on her clit and she screams. However instead of accepting defeat her knee smashes your boys up in to your pubic bone.

She rolls pushes you of her and you land beside her on your stomach, drooling on the ground. You feel both of her hands on your shoulders and her knee press between your legs slowly "you ready?" She whispers in your ear. "Please," you try to beg but she starts slamming her knee repeatedly into your already weakend testicles.

As your sister destroys your manhood you survey the scene and its not good. You can hardly see any boys standing but theres still gotta be at least 40 girls, and the guys you can see are being ganged up on.

A group of girls circle around where you're being pulverized when suddenly.

*POP*

One of your balls explode and cum shoots into your speedo. "Please," your shaking uncontrollably "i surrender!"

The girls roar with laughter as she slams her knee down as hard as she can.

*POP*

More cum shoots out of you dick into your speedo. After your sister lets go of you and you roll to your back. She reaches down and grabs your cock in your shorts and pulls hard on it making you scream.

The girls cheer, their battle is won, they're the superior gender.