You came home for Christmas without your girlfriend this year, and your sister can tell somethings wrong. She pulls you aside during the holidays and asks what's going on. "Are you guys breaking up? You can tell me... I just want to make sure you're okay!" It slowly comes out that your girlfriend hasnt been keeping you sexually satisfied... like, at all. She doesn't suck your dick, and hasn't let you have sex with the lights on since you first started dating. Your sister is shocked, and tells you this is NOT normal. "You need a release!" She seems concerned but she's also acting a little... flirty? You try to pull away, but she just amps it up - putting her hand on your thigh, leaning in to whisper in your ear... "What? You don't think I'm hot?" She pouts, and you feel your cock throbbing for her. Are you dreaming? Your sister is offering to do all the things your girlfriend doesn't do! You want it so bad but you know you shouldn't. FINALLY she persuades you to give in and let her have her way with your cock. She dirty talks about how much better she is than your girlfriend while you make her squirt multiple times with your big dick. "If you're going to cheat on your girlfriend don't you want to do it right? Cum in your sister" she moans and you shoot a big load right inside her tight little pussy.