In a split second we both realized what had just happed but were both too far gone to care. She tried to get back upright but it only made my cock sink in and out of her ass. I was fucking her ass! Three times she tried to get upright but each time she only managed to pump my cock in her ass. Before long I realized she was not trying to get up, she was lifting her ass up and down helping me fuck her ass.
“Fuck my ass baby brother, take my ass hard,” she screamed.
“You want my ass? It’s yours. Just fuck me hard. Sink that hard cock deep in my ass,” she said almost hysterically.
Those words were more than I could take. I felt my cock begin that last thrust as the cum boiled from my balls and exploded deep in her ass. She also let out a scream as her orgasm tore through her body. I think we both may have passed out. I woke up in a daze and felt my cock finally getting soft. It slipped out of her ass with a plop.
We both just lay on the floor for several more minutes before I started pushing my back against the material. I felt it give again and heard the material rip. My back was out of the costume. I climbed out slowly, my boxers were covered with cum and pussy juice. As I looked down I could see my cock was still semi hard and poking through the fly in my boxers.
I was covered in sweat and my hair was dripping wet. I rolled on my back and started trying to catch my breath as my sister worked her way out of the ripped opening. As I watched her climb out of the costume, I could see she was a bigger mess than me. Her hair was matted together and all in her face. She had lost her bikini bottoms and I could not help but admire her waxed, smooth pussy.
I looked up and saw that her bikini top had ripped and her breasts were totally free. As she struggled out of the costume I watched mesmerized as her huge breasts would swing back and forth like a metronome. It was the first time I had ever seen her totally naked and I could not stop myself from looking. She was covered in sweat and cum like me, her face was flushed with wet sweaty hair hanging in her face and her nipples were as hard as erasers. She freed herself at last and rolled on the floor next to me.
We sat looking at each other for several minutes. The more I looked at her covered in sweat and cum, the more excited I became. The blood flooded back to my cock in such a rush that it almost hurt as it sprang up on its own. With no idea what to say or do I could only look at the glow on her face to tell she had enjoyed it as much as me.
After a while we both caught our breath then she leaned over me and kissed me. It was no sister kiss, it was a kiss of a woman that wanted to be fucked. She crawled up on me with her tongue in my throat and started rubbing her huge breasts against my chest. No longer being hindered by the costume she reached back and guided me into her dripping pussy and started riding me.
She started moaning as I tried to match her down thrust with my own upward thrust. She started kissing my face and biting my neck. She grabbed my hair and thrust her tits into my face.