She arrives quickly.

A knock on the door, ignoring the doorbell, alerts you to her arrival. You open up and let her in. She squeezes past you, then waddles further as you lock up. She is dressed in spandex so you can see every detail.
"Tessa. Pleased to meet you. Why don't you get naked so I can see what I have to work with."
"Ah?"
"Ah? Ah what? Very well you can suck it."
Tessa pulls out this long tube of flesh that was curving around under her clothes. She hands you the end and leans back against the sofa.
"Ah..."
"Yes, go ahead open wide and do your best."
You probably shouldn't have said 'ah' so much. She has her hands resting across the top shelf of her breasts. She stares at you. She is eyeing you intently. You put your lips on the end, and stick your tongue out and run it over the surface. She shivers and a dollop of precum oozes out into your mouth. You swallow, and try again, but sucking too this time. A larger dollop comes out.
"Do you like blowjobs? Or would you rather titfucks?"
"Well I always like a good titfuck," you admit.
"Good because you suck at this."
"Pun?"
"No. Your mouth is too small."
"Ah."
"How loose is your butt? Can you take me?" You eyeball her.
"I don't think the whole length."
"Not yet, I wouldn't think. Alright, go ahead and stick it up your butt, I'll make the necessary changes." She moves a bit and plops down on the sofa. You strip off your clothes. You do it slowly, especially the shorts. You gyrate a bit as you do.
"You like to move like that?"
"I was just doing it for you."
"You will look great doing that later."
"I will do it whenever you like," you tell her as you spread your cheeks and then let go after pressing her to you, trapping her end there. You gyrate your ass for her, swaying back and forth as you feel the wetness begin to coat you completely. Then zeroing in, you let it slip in slightly. You keep moving for her, since you see that the volume of liquid is greater as you do.
"I'm going to cum, pull it out and rub it around after you take a few up the ass," Tessa instructs.
"You got it," you tell her after you feel a few ropes of cum jet up your butt. You keep it trapped between your cheeks and catch the runoff and smear it all over until your ass is not only shiny but white and dripping wet with her cum.
"Good coating. It will make sure the growth remains even."
"But..."
"Yes, butt. You coaxed out a lot of precum so you should get quite big. I would recommend thongs from now on."