Anyone who have seen yr sister getting fucked by others

[srich]

Our parents were away for the evening. She invited her boyfriend over. We were all watching tv for a while when I decided to go to my room. A bit later, I heard a sound like a bed creaking. I went to investigate, and I saw that my sister's bedroom door was slightly open. I looked inside and and saw my sister getting slammed from behind. they were facing away from me, so they didn't see me. I pulled my dick out and started wanking while watching them. She wasn't moaning, but breathing very hard and loud. He started fucking harder and faster. My sister looked back, I swear she saw me, but they didn't stop. I was so hard, and jerking fast. He then pulled out and started to shoot on her back. I then ran back to my room and shot the biggest load ever. She never said a word to me about it