Your sister comes over unannounced. For weeks now she has been annoying you, obsessed with pregnancy, crying, ringing in the middle of the night to talk about her inability to be bred. She comes out with some crazy statistics about families breeding together and how there is a higher probability of success. She starts showing you her tits telling you they were made for breastfeeding, her breeding slit.... Shows you how she would push out a baby and somehow your dick is in her. She gets loud and crazy on top of you... Going on about her implantation needs and how ripe she is. You lose control and leave her with a DNA matching Creampie from heaven. She's definately pregnant...there is no way she can't be after her pussy is left leaking with the biggest deepest load she ever received. You are the best big brother ever!