Started playing a prank on my sister who was taking an afternoon nap with her nipples visible through her clothes! I twisted and turned her sensitive nipples, causing her to arch her back in unexpected ecstasy! I inserted myself into my drowsy sister and started thrusting, but she woke up! Even so, my sister agreed completely, saying 'It feels good, do whatever you want.' We ended up having forbidden intercourse with internal ejaculation!
