A/N: This is for the Crossover Challenge on HPFC. It's my first attempt at a humor piece, so hopefully I've done OK. Please review!

I don't own Harry Potter, or South Park (but I do worship them). And, because I want to cover my behind, South Park is pretty offensive, with the stuff that spews out of Cartman's mouth as some of the worst. I'm just trying to keep the characters as canon as possible, the views of Cartman don't reflect the views of the author.

"We don't have a teacher, substitute today!" the class was singing. Many were running around the room, throwing anything they could get their hands on, Butters was in the far corner muttering about destroying the revelers and about 'Professor Chaos'.

"Now, settle down, mmm'kay," Mr. Mackey entered the room, and the class slowly made their way to their seats. "Mr. Garrison is out at his convention today..."

"Yeah, 'men who used to be women who used to be men'. Probably huge," Cartman said loudly. A few students chuckled.

"So you'll be having a substitute today. And since no substitutes from the district are willing to come back to this classroom I've had to call outside help. Principal Victoria has a distant cousin who lives in England, and he was willing to come substitute today..."

"Woah, dude!" Kyle shouted. "You had to go all the way to England to find a sub?"

"Yes. Mr. Snape comes highly recommended, so behave, mmm'kay."

At these words Snape sulked into the room. He was wearing a black suit, and even without the billowing effect of his robes his demeanor made him seem twice his size. He shot an annoyed look over the gasping class.

"Good luck, Mr. Snape, mmm'kay," Mackay said as he quickly left.

"I don't need luck," Snape snarled, glaring at each child.

"Oh, balls," Cartman groaned.

"Quiet!" Snape barked at him, striding over to stand above him. "Is there something you want to share with the rest of the class?" he hissed dangerously.

"N... n...no," Cartman stammered.

"No, what?"

"No, sir."

Snape turned towards the blackboard to hastily scribble his name.

"Dude, did you see him? He was hella intimidated by me," Cartman whispered to Stan, Kyle, and Kenny.

"No he wasn't, fatass," Kyle hissed back.

"Yeah, dude," Stan threw in. "You practically shit your pants."

"Mmm mmmm mm mmmm mmmmmm," Kenny threw in.

"Dude, I totally wasn't scared," Cartman said, puffing out his chest, but he squeaked in terror as Snape dropped a heavy book onto the teacher's desk.

"Could any one of you numbskulls tell me where in the book you happened to be?" he growled.

"We were on page sixty four," Wendy said before her hand was fully raised.

"Let me make this abundantly clear, you insufferable know it all," Snape glared down at her as she sunk lower in her seat. "In my class students speak when they are called on, and not when they know the answer. Now open your books!" he barked at the class.

There was a mad scramble as the students tried to find the right page.

"You!" Snape pointed at Tweek.

"Agh!" Tweek shouted as he fell out of his chair.

Snape rubbed his temples as Tweek got back into his seat. "Start reading," he commanded.

"In the fifth episode of the third season of Melrose Place we find that..."

"What is that garbage?" Snape growled, picking up the book.

"It's what Mr. Garrison assigned us," Kyle offered.

"And is it really that essential to your education that you study a television show?"

"Mr. Garrison thinks so."

Snape slammed his copy of the book shut. "Nevermind, I will not waste my time and yours by having you read this drivel in class. We'll move on. I understand you have oral book reports due today. Let's get those over with. First up," he surveyed the class. Cartman was obviously praying. "You, Eric, up here now."

"Son of a bitch," Cartman muttered under his breath as he climbed out of his chair.

"What was that?" Snape asked.

"I'm glad I got picked," Cartman said loudly. "I'm going to kill you," he added softly.

"Not if I get the chance first," Snape said, and if looks could kill he would have been right. "Give your report!"

"My report is on The Hitchhikers Guide to the Galaxy," Cartman started loudly. "It's a wonderful book, have you had a chance to read it, Mr. Snape?" He was hoping his Simpsons ploy would work.

"No, and I have the feeling that you haven't either," Snape sneered. "Back to your seat, you get an F."

"Weak," Cartman groaned, returning to his chair.

"Serves you right, fatass," Kyle smiled at him.

"Shut up you fucking Jew!" Cartman screamed.

"Eric!" Snape snapped, and Cartman jumped in his chair. "What did you just call him?"

"A Jew. Because he is, in fact, a Jew."

"I better not hear those words come from your mouth again," Snape said dangerously, leaving the threat unfinished. Cartman's mouth stayed shut, he seemed to know when he met his match.

The morning passed with book report after book report being presented. Most of the class were awarded Cs, Kyle, Token, and Wendy were given Bs. Kenny had to repeat his report four times before Snape threatened to burn his parka if he didn't take it off. His report on the latest issue of Playboy was given an F.

"But that's not fair," Cartman said. "Kenny can't afford a book. His family is too poor."

"He can afford a library card, can he not?" Snape retorted.

"Probably not. They can't afford the fines."

"Shut up, fatass!" Kenny shouted, throwing a binder at Cartman's head, hitting him above the ear.

"Ouch!" Cartman shouted, tears in his eyes. "Did you see that, Mr. Snape? Did you see him hit me?"

"Hopefully it knocked some sense into you," Snape muttered as the lunch bell rang.

The boys hurried from the room, Kenny pulling his parka on.

"That guy is a fucking bitch!" Cartman ranted as soon as they were in the hallway. "He makes Kyle's mom look good."

"Don't you talk about my mother!" Kyle said, kicking him.

"Ouch, stop being such a Jew, Kyle."

"Woah," Stan said, standing between his friends as Snape stalked from the classroom towards the teachers lounge.

"We need to get rid of him, seriously," Cartman said as soon as he was sure Snape couldn't hear him.

"Mmm mm mmmmmmm mm mmmmm mmmmm m mmm mmmm mmm mmmmmm mm," Kenny said.

"Of course you'd like him, he's probably poor like you!"

"You're such a dumbass," Kyle rolled his eyes.

"And he's got a big hook nose. Maybe he's Jewish, like Kyle."

"Shut the fuck up!" Kyle shouted.

After lunch and recess, throughout which Cartman kept throwing out ideas about how to run Snape out of town, the boys headed back to class.

"Or maybe we could tie antlers to his head and tell Jimbo and Ned he's a rare species of deer," Cartman said as they entered the empty classroom.

"Just stop, he'll be gone after today, Mr. Garrison is coming back," Stan said, taking his seat.

"Oh, he left his bag here," Cartman said, walking towards a black bag on the floor. "Let's see what he's got in it." He rooted inside the bag and came up with a small vial of a deep purple liquid. "Maybe it's his blood," he muttered, looking over the vial.

"Mmm, mmmm mmmmmmm mmm mm mmmmm," Kenny said.

"I dare you to drink it, Kenny," Cartman uncorked the bottle and held it towards his friend.

"Mm mmm," Kenny shook his head.

Cartman dug in his pocket. "I'll give you ten dollars," he said, holding the bill towards Kenny.

"Mm," Kenny took the money, shoved it in his pocket, grabbed the vial and downed the liquid. He was fine for a moment, then he fell down on the floor, not moving.

"Oh my God, they killed Kenny!" Stan shouted.

"You bastards!" Kyle added.

"Whom exactly do you think killed Kenny?" Snape's voice sounded behind the trio gathered around Kenny's body, causing them to jump and turn around.

"He's.. he's not dead," Cartman said, propping Kenny's body up. "Hey guys, I'm not dead, and it's certainly not Cartman's fault if I am," he said, moving Kenny's head back and forth with his hand.

"How stupid do you think I am?" Snape growled.

"Mr. Garrison would have fallen for it."

"I'm not Mr. Garrison," Snape snapped. "Now get to your seats." The boys obeyed, leaving Kenny's body on the floor. Snape grabbed his bag, rooted in it, brought out a small stone and shoved it into Kenny's mouth. Kenny sprung up immediately.

"Woah, dude," Stan said in amazement.

"Get to your seat," Snape commanded.

"There's something weird about him," Kyle muttered to Stan.

The afternoon passed slower than the morning, most of the class now realized that there was no point in going against what Snape was saying. But as the clock crept towards the end of the day Cartman was getting anxious.

"Come on, you stupid clock," he muttered, looking up at the clock on the wall for the sixth time in a minute.

"Interested in getting away from me?" Snape stopped the lesson to look at Cartman.

"No, sir," he said, looking innocent. "I love your teaching style. Please, continue."

"I'm so glad I have your permission," Snape snarled.

"You should be glad, you Jew bastard," Cartman grumbled.

"That's it!" Snape growled, spinning around and pointing a stick at Cartman.

Cartman tried to speak, but he couldn't get any words to come out of his mouth. He made a rude gesture at Snape, then struggled to get rid of the invisible force keeping him from talking.

"Dude!" Stan said, smiling.

"Sweet!" Kyle threw in.

"I don't doubt your friends will miss hearing the sound of your voice for the next day or so," Snape smirked at Cartman. "It will return by Monday morning."

Cartman looked up in him in horror as the bell released the class for the weekend. Snape grabbed his bag and was the first one out of the room. Cartman was obviously swearing at him and gesturing him to come back and give him his voice back.

"Cartman, you fatass, the best thing that could happen to us is you not being able to talk for the weekend," Kyle said at his struggling friend. Cartman flipped him the bird and swore silently at him.

"This is awesome," Stan smiled.

"Mm mmm, mmm mmmmm mmmm," Kenny added.

"You know, I learned something today. Even though we didn't like Mr. Snape because he's strict and doesn't take our usual tricks, I shouldn't have been so quick to say I didn't like him, because he made Cartman shut up and that's awesome!"

"Yeah," Stan said as they walked towards the exit of the school, Cartman in a silent hissy fit behind them.

Snape Apparated to Hogsmede and stalked through the town, up through the gates of Hogwarts, and through the school towards the teachers lounge. He extracted a small sack from his pocket and threw it in front of Minerva McGonagall.

She picked it up, looked in it, and smirked. "Not as easy as you thought."

"You set up the most frustrating class in existence on purpose, didn't you?"

"Easiest ten Galleons I've ever earned."