it was a cold winter night and i was sitting in front of the fire when i heard the door bell ring. i got up and opened the door only to find that my sister had come to meet me. she was wearing a tight fitting dress and her sexy figure was showing fully. she came inside and went straight to the fire to get some warmth. as she knelt down her tight trousers slid down a bit and i could see her panty from the top. i started getting the biggest hard on of my life. i could not believe that i could feel this way for my real sister.