Convinces his sister to help him cum

Under the pretext of helping him cum this guy gets to do something he had never done with his sister before. First he tells her that he needs to ejaculate so that his balls don’t hurt and asks her to give him a handjob. As he doesn’t cum the sister agrees to suck him off and then she herself tells him to fuck her so that he can unload his balls at once. The fuck is intense and ends with an internal cumshot that leaves the sister’s pussy dripping with hot cum with the risk of getting her pregnant after releasing all the semen.