Another store is the perfect breeding ground for bold new plans

Twenty minutes later you're balls-deep in your mother's asshole, railing her from behind as she kneels on a yoga mat on the floor of the local fitness store.

"Ungh... How's the, uh... Fuck... Padding?"

"Um, my knees s-still kinda h-hurt," she stammers in reply, shuffling a little and trying to get comfortable.

Yeah, duh... They have to hold up that fat ass--Not to mention my whole body. You let your feet lift off the ground, putting your full weight into every thrust. "Dang... Guess we'll have to try out a few more."

"Hey!" An annoyed voice cries out from behind you, as an employee trips over the empty box of the mat you're currently using. "You can't take those out of the package--"

Luckily, the voice is feminine, so you bust out 'ol reliable: "Get down here. Free dose."

"I--Fuck. Fine."

You don't even look at the young woman as she kneels beside your mother's ass. You just keep thrusting until you feel yourself getting close, then pull out and shove it down the stranger's throat. "Uuuunnngh... Yeah..."

"Huh? Honey, are you almost finished?" Your mom tries to look over her shoulder, but you give her ass a shove and she falls forward. "Ah! What--"

"Rest for a s-sec, Mom," you grunt, your voice shaking as you lock your legs around the sputtering woman's head and unload into her stomach. "I... Fucking... N-no, don't t-turn around..."

"Why not?"

"I'm... I'm soft, and I don't w-want you to see it," you lie, grabbing your latest cocksleeve's hair and using her tight throat to milk the last few drops of jizz out of your pulsing shaft. "I... I guess you're j-just too fat."

"Oh my--No! That's--Oh dear... That's bad," your mother replies, trying to wrap her head around the problem. "If you can't get it up, then... I won't get as many donations, and--And--I'll die!" Suddenly, her voice turns from despair to determination: "...I need to fix this. I need to lose weight even faster."

"Fuck," you mumble, as you release the employee and let her fall to the floor. She's half-conscious, sputtering and coughing up slime.

"Don't cry, sweetie," Mom continues. "We can do this. I'll just... I have to cut out even more food, and exercise lots, and... And..."

Suddenly, you have an idea. A dastardly idea. One that will fuck up your mother's diet, put an end to any notion of exercise, and cause her belly to grow, all at once.

"I know what to do," you begin, helping her to her feet (while keeping her pointed away from the freshly-facefucked woman lying on the floor). "It's so simple--I can't believe I didn't think of it before!"

"What is it, sweetheart?"

"Your birth control pills! You've gotta stop taking them."

"Wh-what? That's not... Isn't that..."

Before any dangerous thoughts can take shape in her addled mind, you plow onwards: "It's perfect! Did you know that birth control causes women to gain weight?"

"Um... Really?"

"Yeah!" Pretty sure that's actually true. "Every pill is, like, six hamburgers!" Pretty sure that's NOT, but whatever.

"But... What if I get pregnant? Your father and I... I went on them after I had you and Cassidy. If I stop..."

"Relax," you reply, giving her massive rear end a reassuring pat--Well, more like a spank, but she barely notices. "When's the last time you slept with Dad?"

"Ummm... A few nights ago, I think... When you and your brother were at that party--"

"Sorry, sorry. I mean when's the last time you fucked him!"

She doesn't bother to reprimand you for your language: she's either forgotten that you shouldn't talk like that, or has given up on trying to change it. "...Oh. Well, uh... I can't remember. Not for a long time, I think--"

"Right, so there's no risk," you say with a grin, before she can ponder the fact that she never has relations with her husband anymore.

"B-but... What about you boys? When you're helping me?"

"We'd never cum inside your pussy," you lie. "You know that, Mom. Don't be stupid."

"Oh, right," she says, nodding. "Sorry, honey. I guess I need a dose soon, huh?"

"Yeah... I guess you do." As you pass through the clothing section, you see the door to the changerooms. I'm gonna need some privacy for this next part... All this talk of birth control has me wanting to nut inside her. She's not fertile YET, but... Practice practice practice, right? Putting your hand back on her ass, you guide her inside.

"Um, where are we going?"

"Gonna get you some new outfits, Mom. Let's get a changeroom ready."

"But we haven't picked any clothes yet?"

"Right, right... Guess I forgot. Tell you what: why don't you go in there, lie on the ground, and spread your legs? That way when I come back in with a new swimsuit or whatever--Y'know, for working out in--I can just slip it right on to you."

"Oh, okay!" Smiling, you mother ducks into one of the booths... Completely missing the look of disgust she gets from another passing customer, a woman who's walking out of the dressing rooms. She glares at your mother's scantily-clad, ridiculously-fat body, and wrinkles her nose as she smells the cum glazing much of her skin.

"Ew," she says under her breath, before spotting you. Then you see a spark in her eyes as an idea takes shape. "Hey, dude... Is that your wife or something?"

"My mom," you reply, almost proudly.

"Ah. Well, uh... Wanna give me a dose? If that's all you have with you, I bet you're all pent up," she says, moving closer and cupping your crotch.

"No thanks... I'm kinda in a hurry." You turn your back on her, heading back out into the store to grab a few skimpy new garments for your mother. "She's waiting for me."