During summer vacation, my sister brought her friend home, but the air conditioner broke, and the room became like a greenhouse! The fan didn't cool her down at all, and she was still covered in sweat, so she took off her jacket and flipped up her skirt, exposing her panties and nipples! I was so nervous seeing my sister and her friend in such a lewd state that I got a full erection... Of course, my sister's friends found out, but they wanted to release their frustration, so I ended up cumming inside my sister's friend and even my sister many times!