(scene opens in Candace's room. Her alarm clock beeps until she smashes it.)
Candace: Today's the day! Me and Jeremy at the new yogurt shop. (Looking at her calendar) Today's the...AHHHH! Friday the 13th!? (Candace runs out of her room screaming, then tumbles downstairs)
Linda: Careful, honey. Your father just had the stairs waxed. Come join us for breakfast.
Candace: (Taking a seat) Friday the 13th. I'm doomed.
Ferb: In Italy, 13 is considered a lucky number.
Phineas: Yeah, Candace. Luck is what you think of it. (A ticket falls out of his cereal box) Neat! A ticket for the next Tiny Cowboy concert.
Candace: (Spits out glass of orange juice) I've been trying to find one of those for weeks! (Her chair breaks a leg and she falls under the table) Hey, where's Perry?
(Perry makes sure nobody is looking and then jumps in his food bowl, entering his lair)
Major Monogram: Morning, Agent P. We have reason to believe that Doofenshmirtz is up to no good. Since today is the infamous Friday the 13th - not that I'd believe in such superstitions - he might just be plotting something to do with his typical everyday bad luck. So you know what to do. (Perry salutes and leaves. Major Monogram then puts on a four-leaf clover necklace)
Carl: Sir, I thought you said you didn't believe in bad luck.
Major Monogram: Just for extra precautions, Carl. Now put on your necklace.
(Perry arrives at Doofenshmirtz Evil Inc. and breaks through a door. Sprinklers are set off.)
Doofenshmirtz: Nice one, Perry the platypus. You've set off my sprinkler system. Here, take this umbrella. (Perry opens the umbrella, but it closes on him, trapping him) Gotcha, Perry the platypus! Don't you know opening umbrellas indoors is considered bad luck.
Perry: Grrrrtttt.
Doofenshmirtz: Which brings me to my brother, Roger. He's got this perpetual streak of good luck, even on Friday the 13th. (Shows video of Roger walking down the street) He can't knock over salt shakers no matter how hard he hits a table, Black cats never cross his path, and walking under ladders...well, nobody does that. Not that it'll be different if he did. (opening curtain) which is why I've invented the Luck Swap-inator. I'll zap Roger and myself with it so that I'll get his good luck, and he'll get my bad luck in return. (slips on banana peel) Whoa... who put that banana peel there? (Falls over and hits his -inator, causing it to blast a beam outside the window)
(Scene shifts to the Flynn-Fletcher backyard, where Stacy arrives)
Stacy: What'cha doin?
Phineas: We're building a fun machine, just for anyone who's afraid of bad luck. Like Candace.
Stacy: C'mon, Candace. Wanna go for some Friday shopping?
Candace: (nervously coming outside) It's not just any Friday. It's Friday the 13th! I'll be plagued with bad luck all day, so tell Jeremy that the date's postponed until tomorrow.
Phineas: You're overreacting, Candace. If it'll make you feel better, I'm gonna wish you good luck. (He and Candace shake hands, when both are hit by the -inator's beam) Huh, don't know what that was.
Stacy: (She and Candace walking away) Cheer up, your day's bound to get better.
Candace: Wait! (Stops and bends over to pick something up) Look what I found. A lucky quarter!
Stacy: See what I mean?
Phineas: Okay, Ferb. Let's get back to... (The fence door suddenly slams into him)
Isabella: Oh my gosh! I'm so sorry, Phineas.
Phineas: That's okay, I'm sure it won't happen agai... (Door hits him again as Buford arrives carrying Baljeet)
Buford: Morning losers. (Doors hits Phineas again)
Irving: Guys, you'll never guess what... (sees Phineas behind door) okay, I'll just come back later.
(Doofenshmirtz walks down the street with a wagon, carrying his -inator and Perry)
Doofenshmirtz: Today's gonna be a great day, Perry the platypus. For me at least. Now which way is City Hall? (As he passes by the mall, the scene goes inside to show the girls shopping)
Candace: I'll take some of these, here you go. (Putting them on the cashier desk, streamers fall from the ceiling) What the?
Cashier: You're our 1000th customer! From now on, you'll get 20% off for every item you purchase here.
Stacy: Congratulations, Candace. Even though I and many other girls are probably green with envy right now.
Candace: I guess Phineas was right. Luck is what you make of it. Now I know how he feels. (Cue to musical number, where Candace finds a $50 bill, wins a lottery, and spends the money on a stuffed Ducky Momo toy. Meanwhile, Phineas steps on a rake, dumped on by a delivery truck, and gets struck by lightning when he adds a flag to the machine)
(Doofenshmirtz arrives at City Hall and knocks the door)
Roger: Well, hello Heinz.
Doofenshmirtz: Hey, Roger. Anything you want to tell me about? (Brief awkward silence)
Roger: Actually, I just came up with his joke. So an anteater and an aardvark walk into a bar...
Doofenshmirtz: (In his mind) Don't worry, Heinz. It'll all be worth it once you steal his good luck. (Perry pulls his arm out of the umbrella trap to check his watch, then puts it back in)
(Scene cuts to the park, where everyone is having fun on Phineas and Ferb's machine)
Isabella: I'm starting to get worried about you, Phineas. Are you sure you're feeling okay?
Phineas: (Shown with a few bandages) You know, despite my unusual streak of bad luck, I'm doing fine.
Baljeet: You know, it's kinda creepy how you're always so positive. (Buford walks toward them with an open jar of honey)
Buford: Hey guys, you got to try this honey, it's good... (Buford trips, causing some honey to stain Phineas' shirt)
Phineas: Hey, at least my shirt tastes sweet. There's no way this could be bad.
Baljeet: (Pointing to a hive) Unless you count that swarm of bees who appear to be attracted to your shirt. (The bees fly towards them)
Phineas: Okay, now I'm a bit concerned. RUN! (The five kids begin running from the swarm of bees, cue Candace and Stacy in town)
Candace: (Carrying two full shopping bags) I don't know how this day can get any better, Stacy. (The kids run past them)
Buford: Run, Candace, Run! (The girls turn around to see the bee swarm and run. Everyone seeks refuge in the yogurt shop, which is quickly surrounded by hundreds of bees)
Phineas: Although I'm not the superstitious type, I'll say my day has been pretty rough. How about you, Candace?
Candace: Actually, my day's been the opposite. Wait a minute, that means our luck must have switched somehow. (They stop to look at Buford, who is scooping honey from Phineas' shirt onto a yogurt cup)
Buford: What? Honey goes good with froyos.
(Back at City Hall)
Roger: So the anteater says to the aardvark "Stop copying me". But... (Behind a drowsy Doofenshmirtz, a black cat approaches Perry and puts on an agent fedora. Then it starts clawing at the umbrella trap)
Doofenshmirtz: Enough, Roger. You see, I have a little joke of my own. I'd like you to meet the Luck Swap-inator... (sees Perry next to it) Perry the platypus, you're free! Get back here! (Doofenshmirtz runs to him, but slips on another banana peel) Not again! Where do these keep coming from? (Smashes into his -inator and it fires again)
Candace: Okay, this occured when we shook hands, so let's do it again. (She and Phineas shake hands)
Phineas: Feel any different?
Candace: Hey look! I found a coupon. Aw, nuts. (Phineas slips on a banana peel, then looks at Buford eating a banana split)
Buford: What?
Isabella: Hold on, Phineas. You said your luck changed when you wished Candace good luck. So Candace, wish Phineas good luck.
Candace: Well it's worth a shot. Good luck, Phineas. (The two shake hands and get hit by the -inator's beam. The bees fly away.)
Jeremy: (walking in) Hey, Candace, you're here early. (Candace walks to him giggling)
Phineas: Well, I guess everything's back to normal. (He and his friends leave)
Isabella: Hey, maybe that fun machine is still in the park.
Buford: Doubt it.
Candace: (Sitting with Jeremy) You'll never believe the luck I've been having today. I even found this coupon.
Jeremy: Uh...Candace. This coupon's expired.
Candace: That figures.
(Credits)
Doofenshmirtz: (Trying to repair his broken -inator) Of all the lousy luck. Now I have to wait until the next Friday the 13th before I come up with another plan like this. I hope you're happy, Perry the platypus. (Perry leaves Doof to tend to his -inator himself) Fine, I don't need you either. (Walks off, but stops in front of another banana peel and turns around) Ha! You're not going to trick me with that again. (A few steps later, he realizes he has just stopped under a ladder, which collapses on him) CURSE YOU, FRIDAY THE 13TH!