Assuming my sister-in-law would never tell Mom, I relentlessly tease her nipples, playing with them day after day. At first, she resisted and felt embarrassed, but after continuous teasing, she became super sensitive and prone to early ejaculation. Now, she orgasms just from lightly touching her nipples, making insertion a breeze! After teasing her relentlessly during the day, I pounded her hard at night, turning her into my sex slave. Developing her is way easier and more enjoyable than trying to find a girlfriend!