And she makes you swallow it

Zoe never lets go of your head. You are **** to kneel there while her thing pumps you full of that icky substance. You try your best to store the overflowing amount of cum combined with your spit under your tongue, but your mouth is smaller than you anticipated and soon you are gagging with how much juice there is. It's almost involuntary the decision to swallow it.

The bulk of it goes down your throat like lumps. Kinda like drinking spoiled milk. Her balls stop twitching under your chin and she finally looses her grip on your curly hair.

You get her cock out of your mouth, a single thread of your spit as a last connection between the two of you. You fall back on your butt, tired from all the exercise. The dicksmelling-free air is an absolute relief to your lungs. Your heart can't stop pounding from what you've just done. You look up to the dickgirl maniac of your sister, an expression of pure bliss rests on your Zoe's face.

You hear her murmuring something you can't quite understand, only being able to make out the words "So... better... pussy..."