Family Ties/Deny being infatuated with your mother.
Despite Heather having your perverted desires dead to rights you shake your head with her nipple still in your mouth. "Ahh God you're such a liar Timmy." Your big sister giggles while releasing your cock, moving to straddle your hips and starting to grind back and forth. "You can't tell me that wouldn't fuck the hell out of her if you ever got the chance."
Though your attempting to stick to your guns your cock pulsating right against Heather's pussy is doing little to support your case. "That's what you want isn't it Timmy. Mommy, naked on top of your, bouncing up and down, taking your cock deep in her pussy while her big titties bounce back and forth." Heather moans as she start grinding that against your cock even hard. That along with her word causes you cock to jerk hard beneath her pussy, seeming to prove that she is on the right track. "It's OK Timmy.., you can tell me how bad you wanna fuck her. Hell, I'd love to watch your screw her."
You can't take it any more and grab Heather by the ass, pinning her pelvic against your hips as your pop her nipple out of your mouth. "Fine! I wanna fuck her so bad. I fucking hate dad, I wish he would just leave so I can have her naked in her bed every night..., with you laying naked right next to her!" You finally confirm.
Heather giggles in hysterical triumph. "Oh I knew it you little horn dog, all these big titties in the house is just driving my poor baby brother nuts." She leans down and gives you a brief but passionate kiss. "As a matter..." Abruptly Heather stops talking as her eyes grow wide. "Oh my God, I just had the best idea!" She announces as she hops off the bed. "Give me 10 minutes and than meet me in mom and dads room..., your going to love it!" Heather beams as she gives you another kiss and heads off your parent's room.
Well, it seems you have 10 minutes to kill. You could: