You're chatting with your sister-in-law Margo on a video call- you have a little crush on her, so when she starts fondling her nipples mindlessly you start to get very aroused. She notices you getting a bit turned on and because she just wants to be helpful she offers to show you her tits. She even asks your bro if it's alright- he doesn't care at all, so she strips for you. Margo knows you haven't gotten laid in a while, so she's just looking out for you. You really need to get off, and because Margo is so supportive and bubbly she is going to help you get there by cheering you on and counting down.