Today was the first time I went to my girlfriend's house. That night we were making love when her sister suddenly opened the door and saw us both making love. I was extremely embarrassed and was about to go apologize to her. As soon as I got to the door, I was able to admire her beautiful giant breasts while she was changing! The next morning, when my girlfriend went to put on makeup and change clothes, she continuously used her big round breasts to seduce me, causing my penis to quickly swell. Even though she really likes her girlfriend, her sister is too attractive! "You don't need to wear a condom when you have sex with me", "You can ejaculate as much sperm into me". She constantly seduces me with things that I can't do with my girlfriend. The thrill of secretly shooting sperm into my girlfriend's older sister's pussy made me extremely excited. When my girlfriend suddenly returned and found out, I still couldn't stop making love to her. In the end, I ejaculated all over her pussy right in front of my girlfriend's eyes!