When I am in the mood, I like to jerk off totally naked. One day, I was stripped totally naked and I was enjoys some me time with my head phones in and my sister walked in without knocking. I was edging so I was laying on my bed with eyes closed, my legs wide open, lightly playing with my penis (I'm about 4" fully hard). I heard something through my head phones and when I opened my eyes, my sister was standing in the doorway staring right at me laughing. I pulled out my head phones, and covered my penis (I only needed one hand) and yelled at her to get out. She gave me the small penis sign and backed out of the room still laughing. I could hear her laughing on the other side of the door. I skipped dinner because I was so embarassed. the next day I tried to pretend that nothing had happened but the second I saw her she started making the small penis sign and calling me "tiny". Later her friends were over and they were all teasing me too. Clearing she had not kept my secret. until now im embarassed to what happened