[The episode begins at the Krusty Krab. Spongebob is flipping two patties and they flop into his head. He takes a deep breath and cooks them in a thought cloud above him.]
Spongebob: Mm, ooh! [takes the patties out of the thought cloud] Order's up!
Squidward: Aah! [grumbles as Spongebob sets the two patties down]
Mr. Krabs: [sighs] Another pair of perfect patties. Hand 'em over, Squidward.
Spongebob: Wait [puts a sesame seed on the bun] Tink. [the seed sparkles] Okay, now they're perfect. [laughs]
[Spongebob and Mr. Krabs laugh and make various silly faces at the same time. Mr. Krabs stops laughing.]
Mr. Krabs: Okay. Enough. [takes the patties] Everybody gets it. Our patties are perfect. Keep them orders coming, boyos! [sings to himself as he delivers the food to two hipster fishes] Orders up! Two Krabby Patties.
Hipster Fish #1: Oh, uh, yeah. I don't know.
Mr. Krabs: Something wrong with the pattiers, sir? [chuckles]
Hipster Fish #1: No. We just want something, like, different.
Mr. Krabs: Oh! [chuckles] New, huh? We've been waiting to test our, uh, our new menu! Uh, how'd you like to be the first to try it?
Hipster Fish #2: Yeah. We like being first.
[Mr. Krabs runs into the kitchen and opens the freezer door.]
Mr. Krabs: Come with me, boyo. [grabs Spongebob and drags him into the freezer]
[The freezer closes its door and, like an elevator, it takes them downstairs into the basement where Mr. Krabs built a secret laboratory underneath his resturant.]
Spongebob: Whoa! What is this place?
Mr. Krabs: It's me secret lab where I experiment on food.
Spongebob: Oh, Mr. Krabs, this looks like madness.
Mr. Krabs: You think this is mad? Ooh, wait 'till you see... [pulls a curtain and reveals a large magnifying glass with large eye looking through] this!
[The large eye turned out to be Sandy.]
Sandy: Howdy, Spongebob! [pushes the magnifying glass up]
Spongebob: Sandy? What are you doing down here?
Sandy: I'm moonlighting as a molecular gastronomist.
Spongebob: What? A maladowin-a-gas-a-whatalist?
Sandy: [pulls down a diageam of an algebraic expression that includes a burger, French fries, a double-helix, and a pi symbol] Eugene here is paying me to science up his menu.
Mr. Krabs: Look, I'm in a hurry. You have this special project.
Sandy: Well, it's a work in process.
[Sandy grabs a pipette and squeezes a drop of a red liquid, into a container. Red liquid grows into a double-helix shape, and forms a red floating, glowing Krabby Patty.]
Sandy: There it is! Your new patty!
Mr. Krabs: Hm.
Spongebob: Wait, no! You can't improve the Krabby Patty! It's perfect perfection that cannot be perfected upon! [puts normal Krabby Patty on top of red glowing Krabby Patty]
Mr. Krabs: Yeah, right. Sensitive to time. [pushes the normal Krabby Patty in Spongebob's head] Make me 200 of these, pronto!
[The scene changes back into the dining room.]
Mr. Krabs: Here you go, gentlemen. Two brand new patties. [serves the hipster fishes the secret patties]
Hipster Fish #1 & #2: Hmm. Huh? [they eat the new secret patties]
Sandy: [comes out with a load of secret patties in a cart] Step right up and get your new, improved patties!
[The customers pile up on top of Sandy and they each get the secret patty.]
Sandy: [feels dizzy] Ah! Uh.
French Narrator: Many Secret Patties Later...
Hipster Fish #2: [texing on his phone] I'm leaving a good review.
Customer: [full from eating the secret patties] So tasty.
Mr. Krabs: [eats the secret patty] Hm. A little bit different, but they taste familiar. [eats the secret patty whole; he burps and feels sick] Well, that wasn't familiar. [burps]
Spongebob: You feeling okay? 'Cause there's sesame seeds growing out of your back.
[Mr. Krabs groans as sesame seeds grow out of his back. His head mutates into a bun. His torso becomes a patty with lettuce. His claws grow out of the top bun. Two crab feet grow out of the bottom bun. Mr. Krabs has completely turned into a Krabby Patty zombie monster and he moans like a zombie.]
Spongebob: [horrified] What's going on?
Sandy: [feels sick] Ohh. Ehh, I never shoulda eaten four. [feels something growing in her] Uh! Ah! [her head becomes a bun] Huh! [her hands grow bigger and her entire boad inside her suit mutates into a Krabby Patty zombie; she growls]
Spongebob: The new patties! They're making everyone change!
[Soon, all of the customers, who ate the secret patty, mutate into Krabby Patty zombies.]
Squidward: [mutates into a Krabby Patty zombie monster] Uh! Oh! [groans]
Spongebob: I gotta get out of here! Ah! Oh! Oh! Oh! Ah! [retreats into the kitchen]
Dave: Maybe I'll pass on this patty. [throws the secret patty in the trashcan]
Krabby Patty Zombie #1: Try this! [grabs part of his body and stuffs it into Dave's mouth and forces it down his throat]
Dave: [feels sick] Ohh! [mutates into a Krabby Patty zombie] Bite my buns.
[The Krabby Patty zombies march out of the Krusty Krabs and begin to wreak havoc across Bikini Bottom. Norton is seen whistling until he bumps into a Krabby Patty zombie.]
Norton: Ooh! [goes to touch the Krabby Patty zombie, but it comes to life]
Krabby Patty Zombie #2: Eat us!
Norton: Ahh! [the Krabby Patty zombie leaps into his throat and they both fuse into one zombie]
Both: Eat us!
[Officer Rob is resting in his police car.]
Radio Dispatcher: Car 521, we have an outbreak on rabid patties.
[Patrick is seen eating an ice cream cone as Krabby Patty zombies sneak up behind him.]
Krabby Patty Zombies: Eat us!
[Patrick eats one of the zombified hipster fishes. The zombified hipster fish moans and leaves. Patrick then mutates into a Krabby Patty zombie.]
Mr. Krabs: Eat me. [gets stopped by Bubble Bass]
Bubble Bass: Really, Krabs? Is this some kind of new promotional gimmick? Surely, you can do better than this, Eugene. I mean, [takes out a pickle from Mr. Krabs' zombified body] you even wanted real pickles on this cheap costume? [eats the pickle] Pretty insulting, if you ask me. [mutates into a giant Krabby Patty zombie and roars]
Mr. Krabs: Eat us.
[Several Krabby Patty zombies shake the Krusty Krab sign where Debbie Rechid and her children are hiding.]
Ryan: Ohh, whoa! Whoa, whoa! [falls off]
Debbie Rechid: Ryan!
Krabby Patty Zombies #2: [grabs part of his body] Uhh, ah! Open wide!
Elderly Krabby Patty Zombie: Here comes the choo-choo.
Ryan: No! Uhh- [eats a part of the zombie] Mm, mm, mmm! That's not so bad. [mutates into a Krabby Patty zombie]
[Back inside the Krusty Krab, Spongebob is hiding in the kitchen.]
Spongebob: All original Krabby Patty, why did we forsake your perfect recipe? [gets grabbed in the head by Sandy] Ohh. [screams and Sandy lets go of him]
Sandy: Chow down, Spongebob!
Spongebob: Um, no thanks. [eats the normal Krabby Patty] Already ate. See?
[Sandy becomes angry and breaks through the window. Spongebob screams and climbs out of the window to escape. Then he climbs into the dumpster to take refuge.]
Spongebob: Maybe I'll be safe in here till all this blows over.
French Narrator: Moments Later...
[Bikini Bottom is completely burned down from the Krabby Patty zombie invasion.]
Perch Perkins: This is Perch Perkins reporting live from the Krusty Krab, where I am one of the three people still unaffected by this rabid patty pandemonium. The second unaffected person is in this dumpster. Care to comment, sir, on the chaos?
Spongebob: [comes out] Perch Perkins, how did you know I was in here?
Perch Perkins: I was napping in this dumpster when you snuck in, seeking refuge.
Squidward: Take a bite! [grabs part of his body and attacks Perch Perkins]
Perch Perkins: No! No!
Spongebob: Wait! Who's the third person not affected?
Perch Perkins: P-P-P-P-P-... P-P-P-P-P-... [gets some of Squidward's Krabby Patty body shoved into his mouth and speaks through his air bubble] Plankton! [struggles as he mutates into a Krabby Patty zombie]
Spongebob: Plankton. The Chum Bucket! [runs out]
Squidward and Perch Perkins: Eat us!
Krabby Patty Zombies: Eat us!
[Spongebob runs to the Chum Bucket, pushing an elderly Krabby Patty zombie in the process. Inside the Chum Bucket, Plankton is stacking bags of chum.]
Plankton: There it is, Karen. 152 bags of Grade B pre-cooked chum and not a single customer's come through that door.
[Spongebob bolts in through the front doors and barricades it with boards and nails.]
Plankton: Spongebob, what are you doing? How are the customers supposed to get in now?
Spongebob: Those aren't customers out there, Plankton. They're all Krabby Patty zombie monsters! And they're forcing everybody to eat them! You and I are the last two survivors!
Plankton: Krabby Patty zombies? Heh. I'll believe it when I see it.
[Suddenly, the Krabby Patty zombie break through the boards and they gather around the Chum Bucket.]
Plankton: Okay, I believe it!
[The Krabby Patty zombies break through the front door and enter inside.]
[The Krabby Patty zombies stuff some of their bodies into Karen's hard drive and her screen turns into a Krabby Patty.]
Karen: [whirring] Consume me.
Plankton: No! [gets grabbed by a zombified Mrs. Puff] Hey!
Mrs. Puff: Have some.
Plankton: No! Wait! I don't want- [Mrs. Puff rubs him on her zombified body and he mutates into a Krabby Patty zombie; she sets him down] Have a slider.
[Spongebob is now the last remaining survivor as the Krabby Patty zombies surround him. He tries to find something to defend himself but he sees two forks-like spoons.]
Spongebob: Oh! [grabs the spoons] Stay back! I've got sporks!
[The Krabby Patty zombies stop and look at each other in confusion. They resume closing in on Spongebob. Spongebob uses the spoons the climb on the bags on chum to get away. The spoons rip one bag open, causing some chum to fall out and land in Patrick's mouth. Patrick eats the chum and he spits the secret patty out, reverting him back to normal.]
Patrick: Boy, do I feel better!
[Spongebob looks down in confusion, but realizes that chum is the antidote to the secret patty's effects.]
Spongebob: Oh, that's it! Chum is the cure.
Patrick: Oh, a patty. [eats the secret patty and changes back into his Krabby Patty zombie form]
Spongebob: [annoyed] Patrick!
Krabby Patty Zombies: Eat us!
Spongebob: No, eat chum. Wah! [punctures open a bag to let chum fall out]
[The chum falls into the mouth of one of the hipster fishes. He eats it, vomits out the secret patty and returns to his normal self.]
Hipster Fish #2: What happened?
Spongebob: [scoops chum down to the Krabby Patty zombies] Yes! Yes!
[Mrs. Puff and another zombie eat the chum. Squidward, Bubble Bass and another zombie also eat the chum. One elderly zombie tries to eat some chum, but gets pushed out of the way by another zombie. Spongebob continues to throw chum down onto the Krabby Patty zombies as Plankton gets covered with it in the process. Spongebob climbs all the way to the top and looks down at the Krabby Patty zombies.]
Spongebob: Maybe I should up the dosage! [rips open a bag and shoots down chum] Ahh! [he shoots chum into the mouths of the last remaining zombies including Perch Perkins and Sandy] And three, two-
[All of the Krabby Patty zombies spit out the secret patties and return to their normal selves. But in the process, they all become sick to the stomach after what had happened to them.]
Squidward: Oh, my cranium.
Bubble Bass: Ehh, I told myself I'd never eat here.
Mr. Krabs: Oh boy, so much for lab-grown patties.
Spongebob: You see, Mr. Krabs, some things don't need scientific reengineering to be delicious. [draws and forms a Krabby Patty in midair] The original Krabby Patty is perfect just the way it is.
Hipster Fish #2: Yeah, you know, after all that, a good, old vintage Krabby Patty sounds pretty good right now.
Hipster Fish #1: Yeah. Vintage Krabby Patties rule!
Mr. Krabs: You're darn tootin', they do! And for the next three minutes, all vintage Krabby Patties in the Krusty Krab are... double the price!
[Everyone runs out of the Chum Bucket and heads back to the Krusty Krab.]
Plankton: Wait! Don't leave now! Who's gonna clean up this mess?!
[The sceen is about to close until Krabby Patty zombified Patrick stops it.]
Patrick: Uhh! [grabs part of his body including his right eye] Have some. [laughs as the screen turns black]