Video Description: Your sister comes into your room clearly upset, and tells you that she's fighting with her new boyfriend! He's gone to a day festival without her, and is partying with his friends, who are all girls - even though your sister asked him not to go! She's been watching his social media stories and it's all videos of him dancing suggestively with his 'friends', acting like he doesn't have a girlfriend at all! Your sister is furious at him and tells you she wants to do something to get revenge on him - she wants to make him think she's cheating on him with another guy! She explains that she had the idea to send him a voice note where it sounds like she's fucking someone, and begs you to help her out by just providing some masculine sounding breathing and moaning in the background, so it's believable... You're a little unsure but you can tell your sister is really upset, so you reluctantly agree to help her out. Your sister is so grateful and thanks you over and over again, saying that she's so excited to make her boyfriend pay! She starts recording a voice note, acting like she's in the middle of having sex, and getting you to moan in the background - but she soon stops the recording, saying that it doesn't sound realistic enough. She climbs on top of your lap so you'll be much closer together, allowing your groans and breathing to be heard better, and picking up the sounds of her body grinding against yours! You're starting to feel quite confused about all this; having your little sister grinding away on your lap is making you feel some things you don't want to feel about your sister... You do your best to moan convincingly as she talks into her phone, but she soon stops again to tell you that it's just not working right. She asks if you can try kissing her neck, so the voice note will pick up the kissy sounds... But soon even that's not good enough, and she begs you to actually kiss her, so that it will sound ultra realistic! You're nervous, but you do want to help your sister, so you shyly begin kissing her, gradually getting more and more passionate until the two of you are making out as you both groan into each other's mouths so the recording can hear.... You've been trying to fight it, but you finally can't stop yourself from getting hard underneath your sister, as she kisses you and grinds her crotch against yours... She notices and you expect her to be grossed out, but she's actually just pleased, and says that she can use this for the recording! She convinces you that you should both get naked, and then the grinding and rubbing together as you kiss will sound even more impressive... Your sister's pussy feels wet against your cock as she slides it back and forth, kissing you sensually and moaning into the phone about how your cock is so hard, and so big... You're struggling to contain yourself by now, so when your sister suggests you could just put it inside her for a bit, you barely hesitate at all! You slide your cock into your sister's pussy and she starts the recording once more, bouncing up and down on your dick as the two of you groan loudly into the phone... You both intended to stop, but it feels so good that you figure you might as well carry on, so that this voice note is the most convincing it could possibly be... Your sister grinds and bounces on your throbbing cock until she cums hard and loud, then tells the phone that you're going to fill her pussy up with all your cum now, so she hopes her boyfriend is having a good time at the festival, because she's realized she can get much better dick elsewhere... You groan one final time and unleash your seed into your sister, shocked at what just happened but glowing with satisfaction... Your sister ends the recording, ecstatic with how it went, kissing you again and thanking you for being such a helpful brother... and then suggesting, maybe in a bit you could try taking some pics with her, to send to her boyfriend...? Just to really drive the message home....