Most people love to sleep nude. At least that is what I was told. I sleep nude and have for a long time. My girlfriend and I live in an apartment building and my girlfriends sister lives next door. We both have keys to each others apartment in case we lock ourselves out. My girlfriend and I work second shift but don't get home until 3AM. We had inventory last week so we all had to change to first shift. All except for me because I work maintenance. So my girlfriend got up and went to work while I was going to bed. Around 11am I here the door open so I call out to my girlfriend thinking she had come home for lunch. It was girlfriends sister. She made her way into the bedroom and jokingly jumped in bed with me under the covers. I tried to get her to leave but she didn't take the hint. Finally I told her I was nude. She didn't believe me so reached to see if I was bullshiting her. She got a sock when she grabbed my naked wood. She didn't expect me to be that big. She gasped and then grabbed me again stroking it. I couldn't help but let her continue stroking me until I came all over. Then she got up and left.