AN: This idea came to me out of nowhere, and what do you know, I have 10,000 words written in less than two days. This story is practically finished, so I can update really quickly, and I will definitely do so if I get some good feedback and people want to see more! Please let me know what you think! I am so excited to share this with you guys.

Takes place after junior year at the start of senior year. Slightly AU. Sally has left for college already and Casey has met Truman, but harbours no romantic feelings for him. Casey and Derek are both single. How I wish Life with Derek could have gone. ;)

Prologue

"Happy Prank Day to me!"

September rolls around and it's senior year. This means more pranks, more partying, and more days off of school due to… 'illnesses.' I am determined to make this the best year of my life. I have already managed to set off the fire alarm without being caught and take over the homecoming pep rally. Next? Well, to do what I do best – annoy my overly dramatic stepsister.

On a Monday I pretend that I'm sick, and when Casey takes The Prince I gather up all of her undergarments from her dresser and get Sam to give me a ride to school.

While everyone is having a dandy old time in homeroom, I line all of the locks on each locker with Casey's bras and panties. I wait outside Casey's classroom, waiting for the bell to ring and leaning against the wall to examine my handy-work. As I predict correctly, she's the first one to walk out, and I run over to her, hastily grabbing her arm and temporarily distracting her from my prank.

"Ugh, Derek. What do you want?" she asks, hoisting her purse further up on her shoulder. "Wait… I thought you stayed home sick!"

"I feel well enough to be at school." I say. "I figured I shouldn't miss a day unless it's absolutely necessary."

She stares at me. "Well… that was rather responsible of you. I'm proud."

People are starting to notice the new 'decorations,' and there are many shouts and bursts of laughter around us. Casey looks over her shoulder at one boy holding up her pink bra by the strap.

"What the-" she says. "Why is Nate holding a bra? Hey, that looks like the one I own." Her face turns red as she realizes I'm still listening to her talk. I hold back a laugh. "Not that you… ever needed to know that." She walks down the hallway, heading to her locker. I follow a ways behind her, watching her stare confusedly at people holding up various undergarments, some of the girls making disgusted faces and screaming 'ew!' The guys' reaction is even funnier… I start to chuckle.

She finally makes it to her locker and sees that a pair of undies are hanging there as well. "Oh, that is just-" She picks the underwear up and examines them. Oh god, I'm about to die of laughter. "These are mine." she says slowly, coming to a realization. "That bra was mine! All of these are-"

And then she sees me staring at her and laughing and she clenches her jaw, her eyes narrowing. Uh oh.

"DER-EK!"

She charges at me, and I take off in the opposite direction like lightning. I didn't quite anticipate her anger. I weave past the other students, my heart racing, not knowing if Casey is still following, but not daring to look back in case she does catch up to me. She's fast for a girl.

I almost make it to the boy's bathroom where I can hide, but as I rush to my destination, I feel my feet slip out from under me, and I land on my butt… right at my English teacher's feet.

I find the culprit of my fall, extracting a silky black bra from under my bum. Someone must have dropped it haphazardly in the hallway. I silently curse this unknown person and get up, trying to look innocent.

"Hello Mr. Riverson, sir." I say, smiling as he glares at me. "I was just-"

"Der-ek!" Oh, come on! Casey approaches me, rage on her face as she holds up her orange panties, waving them in my face angrily."I cannot believe you did this! Out of all the disrespectful, horrible, disgusting, mortifying-" She stops short as she notices Riverson standing there, an appalled look on his face.

"What have you two gotten into this time?" he asks, shaking his head in disbelief.

Casey and I start yelling our explanations at the same time.

"It wasn't me, it was Derek!"

"Well, Casey called me at home and said she had this emergency-"

"He stole all my… personal things and decided to hang them all over the school!"

"And she needed some extra undergarments because she had a little accident."

"And I just know it was him, because no one else has access to that sort of stuff!"

"But I didn't know which pair of undies she wanted, and normally girls like to match their bras and panties,"

"Plus he was laughing hysterically, like the total jerk that he is, and when I started yelling at him, he started running, so that's a pretty clear sign!"

"So I just brought all of them for her so she would have a nice selection, but she didn't seem to appreciate the favour!"

Mr. Riverson holds up his hands for us to stop. It's then that I see Lassiter coming down the hall, and just when I thought things couldn't get any worse…

"What's going on here?" our principal asks, looking dismayed at what Casey and I are holding. I notice the hallway has been cleared of all other students as well, meaning we're both late to first period.

"It appears Derek brought some of Casey's um… things to school and decided to decorate the hallway with them, and she's not very happy about it." Riverson explains before Casey or I can speak.

Lassiter raises his hands to his face and starts to massage his temples. "I really don't want to deal with this today."

Then let me go free! I think, crossing my fingers for luck.

"You know what, sir? I'll deal with them. You just go relax for once." Riverson speaks up, and I groan inwardly. Oh well, better than dealing with Lassiter… hopefully.

Lassiter nods in thanks and heads off to his office, giving me a threatening look. I grin cheesily, shrugging my shoulders.

Riverson starts giving orders as soon as he's gone. "Alright. Casey, Derek, you two clear up this… erm… mess and I'll write you a pass to your next class. You both better be on time to my class today. I'll sort the rest of this problem out then. I'll be in my room when you're done."

He turns on his heel and walks away, and Casey and I are left alone. As soon as Riverson is out of ear and eye sight, Casey starts whipping me with her panties at me like a madwoman.

"HOW – COULD – YOU – DO THAT?" she says between hits, and I cower in fear, not because it hurts, but because she's beating me with her underwear!

She huffs, finally stopping and crossing her arms, scowling at me. "I knew you were a terrible person, but this is the lowest of lows, Derek Venturi!"

"Lighten up, Case!" I say, still holding out my hands in case she decides to strike again. "No one knows they were yours! And look on the bright side – even if they do know, I'm sure you'll be getting a lot more phone numbers for dates now."

I wink at her, and she gives me a disgusted face, hitting me once more with her underwear. "You are infuriating."

"And you are a…" I pause, holding up her bra that I'm still holding to check the tag. "Size 34 C… not bad!"

"UGH!" she screams, and I run down the hall laughing as she chases after me.

"Casey, good to see you." Mr. Riverson says as I take a seat in his class during third period. "Did your first period teacher accept the pass I wrote for you?"

"Yes, thank you." I respond, but it doesn't come out very grateful as I remember the incident from earlier. "I see my barbarian of a stepbrother isn't here yet." I add, pursing my lips.

"No, he's usually the last person anyway." Mr. Riverson says, chuckling.

At that moment Derek rushes into the room right as the late bell rings. "Woo!" he shouts, raising his arms in the air. "Not tardy!" He takes a seat next to me, and I wrinkle my nose.

"Cutting it a little close, aren't you?" I ask sternly.

"I don't know what you're talking about." he says, throwing his backpack under his chair and grabbing a pencil and crinkled up piece of paper from his pocket. He attempts to smooth it out on his desk. "See, I'm totally prepared."

"Oh brother."

"Oh stepbrother, you mean."

I open my mouth to retaliate, but then Mr. Riverson speaks, addressing the class. "Alright, everyone, I have new assignment for you – a project." Everyone groans and mumbles complaints, except for me, of course. I sit up straight and prepare myself to take notes. "And you can thank Derek and Casey for inspiring me this morning."

I sink back down into my chair as everyone looks at me with angry expressions.

"Now don't attack them before I explain what we're going to do!" Mr. Riverson protests. "Your assignment will be…" My fingers scribble furiously, recording his words. "To formulate a prank and perform it at school." I stop writing and look up to stare at my teacher.

"You've got to be kidding me." I say as Derek yells "YES," pumping his fist in the air.

"Now there are a few rules, of course." our teacher continues. I like rules. Rules are good. "You can't do any harm to school property or to students. That means things like setting off rockets, or starting a mosh pit during lunch, or graffiti-ing the school are off limits." A few kids laugh. "And this will be a partner project."

At the mention of 'partners,' the whole class goes haywire. I look round wildly for Emily and our eyes meet. We both smile, silently choosing each other for this project. I turn back around and see Truman winking at me.

"As if." I say under my breath, my nostrils flaring.

"Whoa, whoa, before you get too excited here, I should let you know that I will be choosing your partner." Mr. Riverson says, and everyone lets out a yell of frustration.

"When I call your names, come up and get an assignment paper from my desk." He ignores our disappointment and grabs a sheet of paper, seemingly the one with partner names on it.

"Emily Davis and Maria Molchetti." My heart sinks in my chest. Well, Emily is out of the picture.

Mr. Riverson continues to call out names, and all the while I'm chanting please not Truman over and over again in my head.

"Truman French and Donovan Thomas." I breathe out a sigh of relief, until I look to my left and see Derek still sitting there without an assignment paper. There are only about four people left without partners, and I realize…

"Casey McDonald and Derek Venturi."

AN: The assignment will be explained in full clarity next chapter! Please review if you have the time!