It all goes white.

You feel one squirt. Then another two. Then another four. All four cocks cum at once. The volume of liquid is nothing short of amazing. The fact that it's pumping into you defies words.
"Oh, you are going to make Daddy very fat," you tell them as you feel your belly pressing against your legs and arms.
"C'mon bro, you aren't chickening out?"
"No, no," you tell them as your arms and legs rest on your swelling flesh. "I'll take as much as you want to give, just promise me you will move me around when I get too big to move."
"We wouldn't leave you stranded, dummy," Katie tells you.
By the time you finish, your middle has torn your clothing. Abby and Sue waddle into the room. Sue looks red-faced but erect at the sight in front of her. Abby just walks up to you and aims her cock hole at your mouth. You open and tongue her as she runs herself.
"Abby! Didn't we just get done talking about this?!?"
"You said no fucking Daddy, does it look like I'm fucking him?"
"I'm warning you, Abby. I'm gonna stick my dick up your ass if you don't stop!"
"Who says I won't like it? Daddy does, enough to take four cocks at once! Stick it in me, Mom!"
Abby takes a wider stance and thrusts her round butt out. She stops rubbing her cock to spread her cheeks in invitation. You look her in the eyes. She winks. Then her eyes go wide and cum blasts into your mouth. Her mouth is an 'O'. Her belly grows to bump yours as cum spills from your lips onto them. You feel activity on your other end as four rehardening cocks fuck you again.
"I think I'm going to take after Daddy," Abby tells you.
"Where is it all going to go? You stack tits on your balls as it is! You have no room for anything between!"
"Oh, Daddy, don't be silly. How am I supposed to have babies if I can't let my belly swell?" You don't know how to tell her she's not like other girls.
"Ah, about that..."
"You didn't knock her up, did you?" Sue demands.
"How can I possibly have done that?"
"By cumming in my pussy, duh. How did you make me?"
"Your what?"
"Thing between my legs. Cum goes in it, babies come out."
"Your...pussy?!?"