I make my sister give me oral sex behind my parents' backs, and share my thoughts in my diary. I've been teaching my obedient sister since she was little that oral sex is a natural thing for siblings to do, and she still believes it. My sister's oral sex techniques are improving every day! Lately, she's become even more erotic, and she's escalating her act, giving me oral sex when our parents can't see! It's seriously crazy! But the thrill of not letting our parents find out, even though they're right next to me, is what gets me excited to the max! In the end, we cross the line...