"You know what? Sure, let's go Tommy," you say.
"Sweet! You're the best Ben!" Tommy replied.
"Alright then. You boys head over to the tub and I'll go fill 'er up," your mom said with a smile, hefting her enormous cock over her shoulder before leaving the room. A drop of precum slowly oozed out her piss slit as she left, leaving a puddle of at least half a gallon of the viscous fluid on the floor behind her. If her pre alone left a mess like that, you couldn't wait to see how much actually cum she had.
"C'mon, Ben! Or rather "cum on" Ben!" Tommy laughed to himself, leaping over your mom's pre puddle as he ran towards the bathroom. You gave one last look at your sister who was still eagerly fellating and titfucking herself, much too busy to join you at the moment. You weren't even sure she could get out of bed with all those modifications...
When you entered the bathroom you saw Tommy had already stripped off all his clothes, his small, prepubescent penis rock hard already. Your mother however was nowhere to be seen. You also noticed that the bathtub was much bigger and deeper than it used to be, like a massive jacuzzi. Perhaps it was built for these cum baths?
"I love when we get to do this together!" Tommy said excitedly. "It's gonna take Mom a little while to fill up the tub though. Wanna have some fun while we wait...?" Your little brother went over to the edge of the tub and leaned over, sticking out his cute round butt and shaking it seductively. Your erection had not subsided after his blowjob thanks to the copious amounts of sexual stimulation you've been surrounded with, and a nice warm hole sounded like the perfect place to stick it right now. You also casually added a little extra jiggle to his booty as he shook it to make it that much more enticing.
Your knelt behind Tommy and lifted him off his feet until his ass was level with your face while bent over the edge of the tub. You spread his newly enhanced cheeks to find they weren't the only part that had been thickened up by your change. His anus had also changed into a thick, juicy brown donut in his deep valley. You immediately buried your face in his pillowy boy butt, your nose planted in his fat boihole while you licked his small balls and taint. His smooth skin smelled and tasted of sweat and boyish musk which you felt yourself quickly becoming addicted to. You ran your tongue over Tommy's small, delicate testicles all the way up to his puckered hole, his legs kicking in delight as you teased him.
"Mmmm, Ben, that feels so good!" Tommy moaned as you devoured his tight chocolate chute, slurping and licking and probing it until it looked sufficiently lubed. You then stood up and pressed your dick against his sopping wet bussy and pushed, slipping inside with surprising ease. His asshole easily swallowed your entire meat rod, squeezing it tightly the whole way down. He had already been quite skilled at making you cum with his mouth; you had a feeling you were going to last even less time in his butt. "Mphh... You're so big..."
As you started to thrust into Tommy's tantalizing hole you looked down in the tub past him and spotted an incredibly strange sight. The bathtub had no faucet that you could see, only a drain. In place of the faucet was a massive disc of pink rubbery material with a rather sexual looking slit down the middle. It was at least as big around as a playground obstacle pipe, big enough for even you to easily crawl through. Since most of your brain power was focused on plowing Tommy's ass you couldn't quite process what you were looking at until you heard a noise coming from inside of it. A long, sticky SSSCCCHHHHLLLLPPPPP like something sliding though it. Soon the slit begin to open by itself, and out popped the head of the biggest penis you'd ever seen!
"Man, I always forget how big Mom's penis gets," Tommy giggles while you continue fucking him. Your mom had been massive before when she was flaccid, but now you were seeing the beast fully hard and almost couldn't believe your eyes. It went from being at thick as your leg to thicker than your waist, though you had no idea how long it could be with much of it hidden in the hole in the wall which you had just come to realize was a gigantic sex sleeve. Her overpowering musk filled the room in seconds.
SSSCHLLPPP
SCHHLLRRPPP
SSHHHHLLLPPP
The monstrous cock began to thrust in and out of the hole with loud, sloppy noises echoing against the bathroom walls, and through the wall you could hear your mom moaning in pleasure. It was incredible how your she could move that thing with such ease; you weren't even gonna try to figure out where she got all the blood to fill an erection bigger than her own body. Precum began to gush out of her huge piss slit by the gallon and quickly pooled in the tub.
"Hey, how about we get in there and get ready!" Ben suggested, detaching his ass from your shaft with a satisfying pop and getting into the tub. He lead you in and had you sit down first before planting himself in your lap, his asshole greedily swallowing your cock once again. You resumed thrusting into his tight butt while the gigantic cock thrusted at you, flinging sweet, sticky pre all over you both. From this angle her piss hole looked big enough to swallow both of you right up if she thrusted far enough...
"Oh I think she's getting close!" Tommy bounced excitedly on your dick.
"I'm getting close too," you grunted back. This only made Tommy bounce even faster, his plump asshole trying to milk your dick for everything it was worth. You could feel the load welling up in your balls, and just as you started to erupt you heard a moan from through the wall and saw your mom's urethra begin to expand.
SSSSSSSSSPPPPPPPPLLLLLLLLLOOOOOOOOOOOUUUUUUUURRRRRRRRRTTTTTTTTT< br />
An explosion of hot, white semen slammed into you and Tommy, instantly drenching you in your mom's thick futa seed!
SSSSSSSSPPPPPPPPPPLLLLLLLLLLLLLUUUUUUUURRRRRRCCCCHHHHH
Another blast just as powerful followed up, more thick splooge sticking to your skin. You could hear Tommy laughing in delight but the dense jizz prevented you from opening your eyes.
More and more ropes of cum drenched the two of you for the next few minutes until you were simply an unrecognizable mess. Gallons of hot, smelly sperm filled the tub to the brim as you pumped your own loaf into Tommy's ass which was microscopic by comparison.
Finally as the semen was just beginning to drip over the edge it seemed your mother had finally calmed down. You couldn't believe how much semen she pumped out, more than you ever thought you'd produce and 10 lifetimes. While it was gooey and sticky it was quite comfortable being submerged up to your neck, covering your body in a wonderful warmth that seemed to soak into your body. You cupped some in your hands and brought it to your mouth to taste. It was almost thick enough to chew, and the taste was almost indescribably delicious, with only one word coming to mind: virile. You almost felt like you'd get pregnant just being in it, and you weren't even a girl (at this moment anyway).
"Ahhh, this feels so good..." Tommy sighed, leaning back against you as the lower half of his face dipped below the yellowish white goop. You could hear him slurping some of it up as well, he certainly was a cum hungry boy. You also felt something up against your feet which you were pretty sure was your mom's dick, seems she hadn't pulled out quite yet.
What happened next?