Stepping my sister

When she was in college my sister was hot hot hot. She wasn’t gorgeous in the face but she was attractive. It was her body that was smoking hot. She had a slender build and big tits. Her build made her tits look bigger ang her boobs made her build look slender. Her ass had just the right amount of junk. She had always been a good quiet girl. Then she got a job as a cocktail waitress during the summers. Men were always hitting on her and she started being more open and flirty. This even spilled over into me. She was always making sexual remarks to me or even letting me look down her shirt even though I was her 4years younger brother The day mom and dad left for a vacation finally came. She had just got home from work and still had on the tight dress they all wore. It buttononed all the way down the front and was fairly short. I made a joke that we were alone at last. She told me I wouldn’t know what to do with her and slapped me hard across the ass. She took off running for the house and I chased her I trapped her in her room before she could shut the door. She asked what I was going to do. I told her I ought to spank her bare ass. She laughed and told me I didn’t have the nerve to undress her even if she let me. I asked if that was a dare and she put her hands on her hips and smiled at me. I walked to her and with shaky hands started unbuttoning her dress. When I had it open to the navel I looked up at her and said that I was going to do it. She just shrugged. I got it all unbuttoned and reached up and pulled it back off her shoulders and let it drop to the floor. My hot big sister stood before me in her bra and panties. She said alright you proved it. I told her oh no. The deal was I stripped her bare. She stood looking at me and finally said ok. I moved behind her and unhooked her bra. She pulled it off herself and I looked over her shoulder at her beautiful boobs. I ran my fingers inside her panties and slid them down to her ankles. The sight of that ass made my cock rock hard. She turned to give me the full view and then said ok your done. I reached out and in one smooth motion grabbed her wrist sat down on the edge of her bed and pulled her face down across my lap. I swatted her gorgeous bare as s 4 or 5 times then let her up. She stood in front o me and looked over her shoulder at her ass in the vanity mirror and said you left red hand prints on my butt. I told her be careful what she dares me to do and walked out.