Sherb x Muff

Sherbert ran into the girls' toilet and slammed the door shut, then again as it bounced open. She dropped her bag on the floor and slapped her forehead.
"S-s-stupid!"
She grabbed the tented hem of her school uniform's skirt and pulled it up, clamping it in her mouth so both hands were free to reach back down and into her plain white panties.
"G-gotta..."
Her huge hard cock sprang out, already erect from when she fell asleep during dance comittee. Her hands started to run up and down it, gently stroking. Sherbert softened and relaxed into the tiled wall behind her as she continued to masturbate, enjoying the feeling of satisfying her urgent need. That awful skate gang had, had, almost found her out, they'd almost seen her when her skirt was raised up...
"H-hhf, hhf, hnf..."
Precum gently leaked out of the tip, letting Sherbert run her hands through it and lubricate the rest of her shaft. She twitched her hips toward a little, wanting the wonderful sensations harder and faster-
The bathroom door banged open.
Oh SHIT.

Sherbert screwed her eyes tight, not wanting to see who it was, and not wanting them to see her in such an awful state. Please go, please go, please go! She fumbled with her dick, dropping the skirt from her mouth and trying to cover her shame. After what seemed like hours she gingerly opened one eye. Perhaps they'd run off. They probably had. Nobody wants to see someone like her doing something like that-

It was HER. What was her name? Muffin, something like that. The leader of the gang. The Saluki dog-girl that had woken her up and teased her about falling asleep, almost finding her tent in the process. She'd only just managed to cover herself up with the bag before sprinting out with their jeers following her. And now the head bitch had followed her, standing there in the doorway with her arms crossed across her uniform's shirt and a horrible, awful smirk on her face that said "I know what you were doing".

Sherbert pulled down harder on her skirt as the embarrasment and shame just made her more excited. A small damp patch was threatening to form where the tip pushed out on it.

"Oh, don't stop. You're fine, juuuust fine."
Muffin was leering down at where Sherbert was barely managing to cover herself. The smirk had turned into a grin, and her eyes were bright. Her tongue darted out and licked her lip for a fraction of a second.
"Just pretend I'm not here."
"Wh-why aren't you running? I-I'm a freak!"
"Pfft, nah. Why would I? You look fine to me."
"B-b-but-"
Muffin glanced up to meet Sherbert's eyes.
"Wow, you really get stage-fright, don't you?"
"W-wh-wh-"
"Shhh, it's fine. Just... go back to what you were doing."
Hardly believing what she was doing, Sherbert felt her hands slacken on the skirt and let it fall off her hard dick. Oh god, what was she doing? This bitch was, was, STARING at her as she started to...
She started with nervous, hesitant strokes that barely moved along her shaft. The scrutiny, the shame of being leered at like this was making her harder than ever. More precum was pooling at the tip of her shaft as well.
"Thaaaat's it, keep going. I thought I noticed something odd. You're... Shubert, right?"
"Sh-Sherbert..."
Muffin stretched the name out.
"Sheeeerrberrrrt. Well, Sherbert. It looks like you're in a bit of a jam."
"Y-yeah?"
"You're rock-hard in a school bathroom stall, and too nervous to do anything about it, am I right?"
"Y-yeah."
"That's a shame. A real shame."
"..."
"Tell you what, Sherbert. I'll help you out, but you gotta owe me for it. No questions asked, I'll get rid of your boner and you do something for me in the future. Got it?"
"W-what?"
"Yes or no, girlie? You want me to take care of that?"
Muffin looked back down at Sherbert's now uncovered cock, pointing with one fluffy finger.
"Y-y-yeah, y-yes please..."
"Well then, do what I say and everything will be all right..."
Muffin took a step forward, and then another, and then she was standing right up against Sherbert whose cock was a scant inch away from touching her midriff.
"We're gonna fuck."
Sherbert's eyes went wide as Muffin reached into a pocket and took out a little foil-wrapped... something. She opened it with her sharp teeth on one corner.
"Condom. You've seen one in sex ed?"
"Y-yeah, but-"
"Shh. I'll put it on."
Muffin pulled the orange disk out of the packet and threw the wrapper over her shoulder. She gently leaned in and touched the center to the tip of Sherbert's dick, then slowly and agonisingly rolled it down over the shaft in a lazy motion that just made Sherbert twitch and squeak.
"Now you're gonna put that-" Muffin gave Sherbert's cock a playful stroke, "-inside me. Ever done that to a girl before?"
"No..."
"Here, this way-"
Muffin guided Sherbert to the sinks and clambered up to sit so that her fuzzy hips and knees were level with the top of Sherbert's cock. She edged forward, then pulled up her skirt to reveal a pair of pink panties with a tiny bow. She  squirmed and shuffled them down around her ankles, then flicked it to one side with a deft motion of one foot. Muffin's fingers reached down and gently spread apart her labia to reveal the soft pink folds inside, while one hand waggled in warning.
"Seen this in sex ed, right?"
"R-right..."
"Not as good as the real thing?"
"Y-y-y-"
"Remember, you owe me for this. Promise?"
"P-promise."
Muffin's fingers traced around her labia gently.
"Mmnn. Good. Come push it in. Slooowly."
Sherbert jerked forward and used one hand to line her cock up with Muffin's muff, prodding and sliding the tip up and down. Slowly Sherbert eased inside Muffin, the orange-wrapped shaft sliding into her.
"Nnnngg. Like that."
"H-hhhaaahhh..."
Sherbert blushed as she moaned slightly, the feeling of penetrating Muffin an entirely new set of sensations.
"Now move your hips back and forth. Slide that thing in and out."
She nodded and did as she was told, starting to fuck Muffin with a slow and irregular pace that eventually settled into a steady rhythm as Sherbert found her pace. Shuffling around on the sinktop, Muffin gave ground to Sherbert and eventually let the other girl pin her against the cold tiles on the wall. She reached between her legs and started to get herself off as well, using her free hand to brace on Sherbert's shoulder. Sherbert's gasps of pleasure and the snap-snap-snap of their thighs slapping together were the only sounds audible in the bathroom.
"H-hhaah, I'm, I'm, I'm-"
"Gonna cum, Sherbert?"
"Y-yeaahhh..."
"Do it, then."
Sherbert relaxed a little further and then grimaced, screwing her eyes shut as Muffin felt Sherbert's cock pulse and a small tickling sensation at the tip.
"N-nnaaaahhhhh..."
Muffin gently pushed on Sherbert's shoulder, prompting her to ease out and away.
"Haah, haah, haaahhh..."
"Good?"
"Y-yeah..."
"Remember you promised to owe me."
"Yeah..."
Sherbert stumbled over to a wall and slumped against it, stil wearing the bright orange condom which was now slightly swollen and milky at the tip. Muffin made a small noise in her throat, patted her clothes down, and put one hand on her hip.
"Tell you what. I'll look out for you. Stop the others pushing you around and stuff."
"Y-yeah?"
"They should just grow the fuck up."
"Th-thanks."
"But in return you gotta say you're dating me if anyone asks."
"What!?"
"You owe me, remember?"
"Oh. Yeah..."
"Darn straight. So, I'll get the others off your back, you act like we're dating. Cool?"
"C-cool."
Muffin harrumphed slightly in contentment, picked up her panties and slid them back on before striding out of the girl's bathroom, never looking back. Sherbert gently slid down the wall to the floor, the condom starting to slide off her rapidly-shrinking cock and leak her own cum.

What had just happened?