Does this make my butt look big?

chapter 1

Keith grabbed the boxers from the shelf. He wanted to having something nice looking for him and his girlfriend Alex's 1 year anniversary. The pair he had grabbed were a warm red, made of a silk like material. "Hm..these are nice." He says to himself. He was a reletively fit guy, 6' and a lean 160lbs. Dark black hair and brown eyes, he kept clean shaved all over, just always had.
"Oh those are some of our nicer pairs." A woman's voice comes from behind him, he jumps a bit. "Oh um...really? Thats great, figured I'd try them on..." He says blushing. He turns to see a large woman smiling. Her big double belly pressing through the huge white polo uniform shirt she wore. Her name tag read 'Amy'. "Oh well let me show you to a dressing room. Maybe you'd like me to bring you some other options if those don't do it for you." Amy offered. "Oh uh yeah that would be nice." He says. She waddles ahead, Keith following in tow, trying not to stair at her butt, though it couldn't compare in size to her belly, it was still large and eye catching. Soon they come up to a large changing room in the back corner of the store. "Just call when you want another pair to try on." She tells Keith with a warm playful smile. He nods and steps into the changing room.
After stripping to just his boxers he looks at himself in the full length mirror that filled the wall in front of him. He'd never really had much for body hair or facial hair. When he tried to grow out a beard it was always patchy and even after puberty never grew out any chest hair. He sighed a bit and held up the red silk boxers in front of him, they almost seemed to big for him, as he looked at his butt, it wasn't much there, his legs rather sleek as well. He pulled off the boxers he had worn in and then slipped on the silk ones Amy had suggested, and once.they were up to his wasit he found they fit well. He looked at himself. "Kinda makes it look like I actually have an ass." He jokes to himself. He butt did look fuller in the boxers, though he thought his thighs kinda did to. He shook it off and took them off, not seeing how that fuller look remained. "Uh...is there some other colors or styles I can try?" He called through the door. "How about these?" He heard Amy reply, a plump hand holding a black pair in the same style. "Thanks." He said taking them. These ones seemed bigger too but he pulled them on. Once he had them adjusted he looked in the mirror. A budding plump belly where once there was the hint of abs. He looked himself over. "Maybe just not my style...?" He asked himself. He called for another pair, this time given a pair of briefs with 'HUNK' sprawled on the seat of them in black. He rolled his eyes and chuckled a bit. "Sure why not?" He says and pulls them on, body expanding further as they settled on him.
He kept this up, pair after pair, style and color changing, along with his expanding figure. Pulling on the 10th pair he looked in the mirror he saw a hefty man in place of the modest build he had upon entering the shop. A round belly, that drooped only a bit, but stuck out a like a woman's would if she was nine months along. Pecs long been wrecked with flab, resting on keg gut, each could over flow a large hand with ease, thighs thick and rolls just starting to form around his knees and above his chunky calves, thighs touching all the way to the knees, leading up to a.rather impressive bubble butt. Much like his gut it had grown large, blubbery and yet would not yeild to gravity, the meaty globes dusted at the bottom with cellulite. His rear was the dominate feature to have sprouted on him it seemed, pulling the black man thong he'd had on tight. "Maybe like some nice boxers? They'd hug everything just right I bet." He said seeming unaware of the newly accumulated blubbery bulk. "Sure thing hun! Hows some dark blue ones sound?" Amy suggest. "Perfect!" He calls. She giggles, this would be the perfect pair. She handed them to him over the stall door and he pulled them up, form expanding one last time to turn him from over filled dad bod to rotund fatty. He models to himself, his blubbery rump bouncing about in the skin tight boxers. "Perfect! I'll take them!" He calls out. He grabs his clothes, pulling them on, they grow to match his new obese bulk.
He waddles out, body jiggling, ass most of all, over to the counter to check out. "What are you doing here hun?" A feminine voice calls out. Keiths round cheeks light up red. "Thats Elise! Hide those!" He hisses. Amy giggles and puts the bag under the counter as a busty red head comes up, cheeks and chest generousily covered in freckles. Her green eyes light up seeing her boyfriend. "Hm..what brings my big boy here huh?" She teases. "Oh..just...um...visiting our new neighbor to thanks for the wine as a.house warming gift!" He lies. "Mhm...well I'll be in the food court getting you lunch." She coos strutting off. When he looks away to sigh, Amy gives the bubbly red head a wink as she waves with a big grin, eager to give Keith a warm anniversary party tonight.