So I've been throwing around doing some sort of Opposite Day fic for over a year, and in talking with Brit tonight, I decided to dig up my old draft, modify it, and then publish. So here you go. I may do something else along these lines in the future, some sort of AU fic. We'll see.

"Hey, am I late?" Penny asked, still in her Cheesecake Factory uniform, as she came into the guys' apartment.

"Nope," Leonard said. "We just sat down."

"Ah, Tuesday food," Penny said. "You know, today was so hectic, it was nice to think that I could come home and know exactly what sort of food would be waiting."

"Isn't routine nice?" Sheldon said.

"Most of the time," Penny agreed, taking her seat beside Leonard.

"I still wish we could have changed things up and gotten Italian tonight," Howard said.

"Why would we want to do that?" Sheldon asked.

"Well, we never do anything differently," Leonard said. "It's like pulling teeth to get you to participate in Anything Can Happen Thursday."

"It's not Thursday," Sheldon said. "It's Tuesday. We can do Anything Can Happen Thursday on Thursday."

"I thought that was the third Thursday of every month," Penny said, "not just any Thursday."

"This Thursday is the third Thursday of the month," Bernadette said.

"And on that Thursday, we will shake up our usual routine," Sheldon said. "Unless there's some valid reason for deviating from the norm, I don't see the point."

"Well, I know," Penny said, taking an egg roll off of Leonard's plate, "tomorrow is the middle Wednesday of April."

"What's that got to do with anything?" Howard asked.

"It's Opposite Day!" Penny exclaimed, looking at the other six incredulously. "Where everything is…you know…"

"The opposite?" Raj piped up.

"Exactly!" Penny said.

"Why is everything the opposite?" Sheldon asked.

"I don't know," Penny said. "It just…is."

"Well, that sounds stupid," Sheldon said dismissively.

"I actually think it'd be pretty interesting," Leonard said. "In theory, anyway. Like, what would we all be like?"

"Well," Amy said, "Sheldon and I would have an active sex life."

"No you wouldn't," Bernadette said. "You'd just be unaware of his advances to the point of coming across as not giving a rip."

"You'd be six feet tall," Howard said to his wife.

"And so would you!"

"Leonard would have a higher I.Q. than Sheldon," Amy said.

"Oooh," Howard said. "Sheldon would wear loose saggy pants and a backwards baseball cap."

"He would say things like 'thug' and 'yolo'," Raj piped up.

"Would I be a nerdy girl who spent years crushing on the guy with a PhD in street cred?" Penny asked, flashing Leonard a grin.

"Or you'd be in love with someone else entirely," Leonard said. "And I'd hate Buffy."

"Oooh," Raj said. "Things. just. got. interesting!"

"Let's see. So I would be in love with…" Penny stopped. "Hmmm."

"Trying to decide if it would be Sheldon or Howard?" Leonard asked.

"Yeah."

"I'd have to say…" Leonard studied both of them. "huh, that's tough. You'd never date either of them in a million years."

"So which one wouldn't I date in a million and one years?"

"Me," both Howard and Sheldon said, raising their hands.

"I'm thinking Sheldon," Leonard said.

Penny nodded. "I think I agree."

"I agree too," Amy said. "But you can't be dating Sheldon while he's coming on to an oblivious me."

"You hear that, Howard?" Raj said, leaning toward his friend, "she'd date you in a million years. There is a number!"

"What about you?" Howard asked. "Tomorrow, in theory, you can only talk to women when you're sober?"

"That would be a plot twist," Bernadette acknowledged. "Just like how I would be a housewife while Howard is out making buttloads of money."

"Hey, I'm not a housewife!" Howard protested.

"No, you're not," Bernadette said. "A housewife would cook and do the laundry."

"Oh, slap some Aloe on that burn!" Sheldon said.

"Sheldon would have a tan on Opposite Day," Leonard said.

"You would have a tan on Opposite Day," Penny said.

"And an ugly tushie," he added.

"Wait, does me making buttloads of money mean I have a PhD?" Howard asked.

"You have Sheldon's," Leonard said, "as he's busy trying to get his GED online."

"I don't think Opposite Day Sheldon would be that driven," Raj said.

"Wait, hang on!" Sheldon protested. "I have two PhDs. If Howard has one, which would only happen on Opposite Day, who has the other?"

"Maybe I have both," Howard said.

"I call dibs on his master's degree," Penny said.

"Hold on," Leonard said, "so on Opposite Day, Koothrapali can't talk to men sober, Penny, a year away from wanting six foot tall Howard, is in love with a thug version of Sheldon, who wants to sleep with a clueless Amy. Six foot tall Bernadette is sewing in the home while Howard is out getting tenure, and I am a tanned, tall guy who hates Buffy and can eat cheese without farting?"

"Hey!" Howard said. "You can sleep with Missy!"

"What?" Bernadette asked.

"Missy might actually want you on Opposite Day," Raj said.

"Okay, everybody, stop talking!" Sheldon said, waving his arms and almost hitting Amy in the nose in the process.

They fell silent. "What's wrong?" Bernadette asked, noting the expression on Sheldon's face.

"We can't talk about this anymore," Sheldon said, looking unnerved.

"Why not?" Penny said, "it's fun."

"Look, Penny," Sheldon said, "As crazy as it would all be – Leonard hating Buffy, Howard having a PhD, Raj becoming a socialite in the female circles…" he waved his hand. "It has just occurred to me that under these circumstances, my twin sister would be smarter than me. You know what they say; it's all in good fun until somebody thinks about being out – done by Missy Cooper in intellect."