It was a typical day in Danville. Phineas and Ferb were in their backyard, when Isabella came in, out of breath.

"Sorry I'm late guys!", she said as she came through the gate. "My parents needed some help rearranging my room."

"That's perfectly fine, Isabella.", Ferb said with a familiar smile and a wave of his hand.

His smile, didn't really seem like Ferb's. If Isabella didn't know any better... But it was crazy to guess. So she shrugged it off and headed over to her secret crush, Phineas.

"So, Phineas. Whatcha dooin?", she asked cutely.

Phineas looked up at her silently. Then a small smirk appeared on his face, as if holding back laughter when he looked over to his brother. They exchanged knowledgeable glances and then looked back at Isabella, Ferb smiling more widely than Phineas.

"Can you guess what we've done?", Ferb asked.

"Uh.. No. That's why I was asking Phine-"

The boys bursted out laughing and so did Buford and Baljeet who were sitting nearby. Then Phineas went behind the tree to get something.

"We've swapped minds!", Ferb explained, revealing himself to be Phineas. "Ferb and I were talking about how earlier this Summer it was weird to see Candace in Perry's body, so we thought it would be cool to swap with each other."

"Yes! Was it not clear with how much Ferb was talking?", Baljeet asked.

Ferb, in Phineas' body, then pushed out the machine that made it possible and stood proudly by it, next to Phineas in his body. Isabella stared at the two boys for a moment. The one she loved had his body in one place but his mind was in a body of whom she didn't love. So, which one did she love? Which is the real Phineas? Suddenly overwhelmed by confusion she took a step back and held onto her spinning head, trying to keep focused. Phineas, with Ferb's voice, laughed some and they decided to swap back. With a quick beam-to-the-face, the boys were normal. Ferb's smile was gone and Phineas' familiar, warm, ultra-happy smile returned to his face.

"Wanna try it out with someone?", he asked cheerfully.

Isabella pondered this for a moment. While she did love Phineas for his brains, there WAS a once-in-a-lifetime possibility here for her to take advantage of.

"Sure. How about WE swap bodies?", she asked, smiling more widely at Phineas.

"US?", Phineas asked, feeling a little unsure. "Don't you wanna swap with...someone of your gender first?"

"No. I'm pretty sure it'll be fine.", she said coming over.

Ferb stepped aside, knowing good and well what Isabella was thinking.

"Okay. Sure!", the young boy smiled again. "This'll DEFINITELY be an interesting experiment."

Once the beam was zapped, the two stared down at their bodies for a moment. Phineas in slight confusion, Isabella in absolute, beaming, delight.

"Wow! This IS weird!", Phineas remarked, having to pause and laugh at the high-pitched girly voice saying his words. "Ha ha ha! Isabella, you're voice is so funny sounding with my speech-pattern!"

"AWESOME!", Isabella said in Phineas' voice only to start giggling uncontrollably. "I-I mean this is weird, cause. Well. It is a BOY'S body, but this is so cool! I think this is the most wonderful invention by far, Phineas!"

Isabella turned and smiled dreamily at the boy's mind who was standing next to her, but doing so, in Phineas' body, made everyone burst out laughing. All except for Phineas who was still looking over the new body and clothes, completely oblivious to the rest of the world.

"Stop it! Stop it! That's worse than before!", Buford wheezed between laughs.

Isabella glared at the group of boys, putting her hands on her hips and pouting her lip.

"What do you mean it's worse than before?", she asked, making the boys only laugh harder seeing and hearing Phineas do it all.

"Hey, you know. I'm not sure if this is a side-effect from the ray or just something to do with being a girl, but all of a sudden, I have to use the bathroom.", Phineas noted, starting to walk to the house. "I'll be back in a minute."

"AH-", Ferb began to say before seeing his brother go behind the glass door.

He buried his face into his hand, feeling embarrassed, knowing there really WAS a great difference between boys and girls. As soon as the door closed though and Isabella's body was out of sight, Phineas' body suddenly hugged himself, falling onto the yard's grass and began to squeal and giggle like a fangirl.

"OH MY GOSH THIS IS AMAZING!", Isabella squealed in delight with Phineas' voice. "I'm in PHINEAS' body! I haven't even seen his room but I'm in his BODY!"

"...Hey. Where's Perry?", Ferb asked, looking beside him.

The platypus was already on his way to Doofenshmirtz's penthouse and the secret agent bursted in, ready to fight. The human looked around his inator, hearing the platypus' entrance of broken glass and seemed confused.

"Perry the Platypus?! You're early! AGAIN!", he rolled his eyes in annoyance. "What's up with that? You have more important things to be doing?"

Perry gave a huff. Yeah. He had WAY more important things to be doing than dealing with a moron.

"Well look Perry the Platypus, if you would just WAIT an hour or two, maybe then you wouldn't have to wait quite so long to foil me.", the man began to ramble. "I've barely had time to work on my inator with Roger's constant on and off the phone with me and Vanessa's troubles PLUS Norm."

Perry only leaned against the wall, knowing he was going to be in for a doozy as the man continued.

Meanwhile, mayhem was running amok in the backyard as almost everyone except Ferb was playing around in each other's bodies. Buford and Baljeet had swapped. Phineas is trying to convince Isabella to swap back. And Candace was even confused with a squirrel Ferb quickly caught so it wouldn't do anything harmful with the body. After all, that was his job. Keeping track of everyone in this confusion.

"N-No offense Isabella, but you're skirt's REALLY making my legs feel cold..", Phineas was saying as he tried to push it down again.

"Sorry Phineas but this is just too much fun!", the girl in a boy's body giggled as she hung upside down from the tree branch. "And with your boy body, I don't have to worry about my shirt slipping! HA!"

"Isabella!", Phineas whined.

"Oof!", Buford groaned as he tripped over in Baljeet's body. "Baljeet, what's up with your body and tripping over everything?! I can barely stand up!"

"Oh I am the one with the issues? How can you walk with this much weight?!", Baljeet was saying as the large body wavered back and forth about the yard. "And with such bulky feet!"

He stumbled a bit and leaned against the machine, accidentally causing it to fire off out of the yard. The beam from the machine flew across the city, narrowly missing many possible guinea pigs for its power.

"...And a FINAL thing...!", Heinz was in the middle of saying before there was a flash of green. "Krrrrr!"

...=3