I have an idea. I have done this for several of my Cuck's wives. During near the end of my fucking. Getting ready to inseminate her. This is some thing special.
I will mount and penetrate your wife from behind. I nice sold doggie style. You will have full access to me thrusting into her. When I get ready to shoot ribbons of my seed into her. Grab the back of my cock. Put two fingers on the underside. You will feel my enlarged urethra. That's the vessel that will carry the seed for your child. You will be able to feel it as it pulsates into your wife.
