I might be getting too confusing here, let me know if it's weird. Just writing what comes to mind.

"Try not to be so unintelligent John. It's not bigger on the inside, because technically the box is just a doorway." Sherlock explained, "We stepped through the doors an into another dimension, technically."

"Time and Relative Dimension in Space, TARDIS. As Sherlock so ineloquently explained. I like explaining it, I give it more pizazz!" The Doctor sulked and Amy clasped a hand on his shoulder.

"It's easier to just think of it as alien technology we'll never understand and you have to be a crazy person to get it." She raised one eyebrow first at the Doctor and then at Sherlock, "Us normal folk, like to say it's bigger on the inside, stop making him feel stupid. Come on John, we'll show you around while these two get better acquainted." John followed Amy, River and Rory up the stairs away from the console and Sherlock walked up to the Doctor.

"So, is she giving you any information about how to get us back to normal?" The Doctor asked Sherlock, "I thought the moment I came in here she'd be humming in my head, but I can't hear a thing."

"Odd, that's all I hear. You would think she would know I'm not you in here, I'm me." Sherlock rested his hands on the control panel in front of him and closed his eyes.

"Good, yes, focus on what she's saying." The Doctor clasped his hands together with a soft smile. He cast his eyes upward and turned in a circle, trying to push out a telepathic message reminding the TARDIS he's still himself, even though his body is different.

"No, I'm not focusing on her..." Sherlock began to swipe his hands in front of him, causing the Doctor to stare.

"What... Are you doing?" He asked, tilting his head to the side.

"No talking." Sherlock dug deep into his mind palace to try to find anything on quantum physics he may have retained, but came up empty handed.

"Very well... I'm sure I've got a book I can research." The Doctor said heading to the staircase leading to the library when suddenly, the TARDIS jerked and began to dematerialize, "No no no no no! What are you doing sexy!"

"Sexy?" Sherlock asked, "Never mind, she likes it." The Doctor began desperately flipping switches and trying to get her to stop moving, the whole room shook and the four passengers ran back into the console room.

"What is happening Doctor!" Amy shouted.

"I don't know! She just started going!" The Doctor pulled a lever and River ran up, pushing him out of the way.

"She doesn't like it whatever it is. And the fact that you're not in your own body is causing her a lot of panic. She thinks you're trying to steal her!" River tried to get the TARDIS stabilized, but her eyes widened when she saw where they were going.

"She didn't do this the first time I borrowed her!"

"Because she wanted you to take her, she said she's told you all this before!" Sherlock stated, and the Doctor stared at him.

"Quit talking to her! Tell her to talk to me!"

"Are you jealous Doctor? It's a machine!" Sherlock shouted and the TARDIS jerked forward, causing everyone except River to fall.

"You've upset her!" The Doctor said.

"No, shut up both of you." John said, "Quit bickering, and let her figure it out!"

"Thank you John. Now I've already figured it out. Something is causing us to jump dimensions. I don't know what it is, but we've gone into another parallel universe."

"What! I can't be in a parallel universe! I've got a criminal mastermind to stop!" Sherlock shouted, running his hands through his hair, disappointed to find it was still the Doctor's.

"Why didn't we switch back then? Or switch to someone else?" The Doctor asked, looking around.

"Um, Doctor..." Rory said.

"Not now Rory, we're trying to figure this out."

"No, not Rory."

"What?" The Doctor got up and walked over to the Ponds.

"My god, my nose really is quite large!" Amy said, poking Rory's nose.

"I'm not following..." The Doctor knelt down next to his companions.

"They've swapped minds, Doctor. Rory is Amy and Amy is Rory. It would seem we've got quite the conundrum on our hands." Sherlock joined the three people and then looked back at River and John, "It would seem if we jump anymore dimensions, you two are next."

"Maybe if we jump enough we'll all get back into our own minds?" Amy asked, clearing her throat, "Boy it's weird not hearing my voice when I talk."

"Aye, ya sound like a brute laddy!" Rory said and everyone looked at him, "What, I've always wanted to speak with a Scottish accent, don't judge me."

"Not to sound rude, but I'd rather not switch into River's body, while it's very nice to look at..." John started.

"Oh thank you sweetie," River smiled, interrupting.

"You're welcome, anyways, while it's nice and all, I'm quite partial to my own body." John stood up, looking around.

"I'm sure you're not the only one partial to your body." River said.

"Right, let's go outside and have a look around." Sherlock said, rushing for the doors. They all got up and headed that way, Amy feeling her chest and Rory pulling down his skirt.

"This is weird." Amy said, grabbing Rory's hand, "Wow my skin is soft."

"It would be interesting to try... Well y'know..." Rory thought for a moment, "You know what, now that I think about it, no it wouldn't."

"Oh behave Mr. Pond."

"Williams." He smiled.

"Whatever." Amy smiled back and kissed Rory, "Soft lips too! No wonder you love me!"

"It's not the only reason." They headed out the doors with everyone else. The Doctor was grinning ear to ear.

"Why is he so happy?" Amy asked and everyone pointed at the sky, "Zeppelins?"

DUN DUN DUNNNNN!

Yeah I just wanted to bring in that universe cause they have a Torchwood and therefore would be able to help them more with the mind thing.

Fun fact: My mom's name is Amy Williams. HA! And she's a ginger! Whaaatttt!