I had been going out with my girlfriend for over a year, and everything was "perfect". She stayed at mine, and i sometimes stayed at her house! The problem was, she shared a room with two younger sisters, which was a pain when i we wanted to have sex!! never the less, we had sex when the sisters had gone to sleep, but had to be carefull!!! one night we had been watching friends, and it had got late, both sisters falling asleep! OR SO WE THOUGHT We were in full flow, and were getting a bit noisy! my girlfriend had climbed on my thingy and was now riding me like the was no tommorow. As i sat up to embrace my girlfriends tits, i saw two eyes wide open looking directly at us!!!!!! The 16 yr old sisters eyes shut quick, but i didnt say anything i just left my girlfriend riding me!!! i stared at the sister, hoping she would open her eyes and to my surprise, she looked again.........it was more like stared! she watched us have sex, untill we both came, something i found a massive turn on! i have never said nothing about this, and neither has the sister, it is now half a year on, and i bet she will never see better sex!!!!!!!!