Apparently my sister recently got a boyfriend... Wanting to be praised by her boyfriend, I (the older brother) was made to practice my blowjob skills. "We're brother and sister, but it's okay if it's just a blowjob, right?" she said, and so my sister began practicing her blowjob skills. "Hey, big brother! Do it again!!!" Even though he had already ejaculated, my sister continued to suck without stopping, with the sperm still in her mouth, making him ejaculate repeatedly. She kneaded and toyed with my dick until it went numb. My sister was more serious than I expected...