Family Ties/Yank Heather's pants and panties down to continue your munching on her pussy.
With your head against Heather's tits and you lips locked with her you begin to slide your hand up her her thighs and hips in search of the waist band of her sweatpants. You can tell from the lack of bumps under that she isn't wearing any panties. Heather is still moaning into your mouth so you grab her sweats and yank them down her legs causing her to jump in surprise as her clean shaven pussy is exposed to you hungry eyes.
"Timmy! What are you....."
You cut her words off by diving tongue first into your cunny as start to face fuck her, making sure to drag you nose against her hardened clit with impalement of you tongue. Your sister's hand goes straight to the back of you head as she shimmies down the seat slightly, offering you better access to her pussy. "Fuck! Timmy..., ahhh Jake never would do this for me!" Heather moans, grinding her pussy against your face while you continue to tongue fuck her.
Heather doesn't last long with how hard you're going at her slit and soon her entire body is quacking. "Oh God! Timmy, you're going to make me cum." She whines while the wall of her pussy start to tighten around you tongue. "I'm gonna fuckin' cum all over your adorable fucking face!"
Wanting to make sure you send her right over the edge into and orgasmic abyss you with draw your tongue latch onto her clit and start sucking it as hard as you sucked her nipples just a few minutes ago. Heather nearly bounces off the driver seat with as hard as her climax hit but you don't stop sucking her clitty for an instant. "Oh fuck fuck fuck!!! I'm cumming. Jesus Christ I'm cumming all over my baby brother's face." Heather says, almost crying at this point.
Eventually she can't handle any more and has to push your head away from her sopping wet pussy. "Oh god Timmy.., I can't..., I.... ahhh fuck!" She groans as you kneel back up with the product of her climax dripping from your chin. After a few moments of Heather enjoying her post orgasmic bliss, she opens her eyes and looks down at you with her chest still heaving.
"Did you like that Heather?" You ask with a giggle.
"What the hell do you think?" She says with a playful yet sinister chuckle before grabbing your head and ramming her lips onto your to kiss you deeply.
After a few moments of making out she slumps back in the driver seat and pulls you along with her so you can lay on top of her mostly exposed body. "Did I lick your cunny better then Jake?"
"Oh fuck yes.., damn near as good as Nicole does." She moans as she gently pushes you up by the shoulders. "In fact..." Heather starts as she guides you back to the passenger seat before dropping to her knees in front of you. "I think my wonderful baby brother has earned him self an early birthday present." She tells you, quickly undoing the latches of your overall and yanking them down along with you boxers, exposing your cock. "What do you think Timmy?" She asks, grasping your cock and giving the head a slow, exaggerated kiss. "Where do you want to put this big bone?"