While at a family holiday party you notice your sister-in-law break away from the party and walk upstairs alone. You follow her upstairs worried that something might be wrong. In a guest bedroom she complains about how boring the party is and how irritated she is with her husband. You agree with her that he is being a bit of an asshole. She confesses to you that she thinks you are the more attractive brother. She then suggests a way to make this party more interesting: the two of you can fool around! You’re hesitant. She is a very attractive woman, but she is married to your brother. Plus, your family is downstairs. What if someone caught the two of you fucking? She just smiles and says that cheating secretly will just make the sex even hotter. She starts to coax you into agreeing by stripping out of her clothes. She shows off her round breasts and juicy ass. You immediately get a boner. You finally decide that you need to fuck her, but it has to be a quicky. She gets on all fours and you get behind her and slide your dick into her wet pussy. She says that you are much bigger and better than her husband. You pound her pussy the way she asks you to, making her ass clap on your dick. She starts moaning louder and louder, so you fuck her hard to cum quick before anyone hears. After filling her cunt up with cum, you two decide to quickly dress and return to the party with your naughty secret