Your slutty sister goes to her friends annual halloween party. You were invited too but you didn't tell her you were going. You were going to prank her, but then you realized how much of a slut she was. She was trying to hook up with guys at the party, even ones she didn't know. You were wearing a mask, and she had no idea you were her brother and she came on to you. She ends up blowing you and getting railed by you at this party with no idea it was you behind the mask. You give it to your little slut sister. Then you reveal to her that it's you!! She is horrified, mortified and crying and you black-mail her into blowing you and juicing your cock again - but this time you blow a huge load in her mouth.