This episode starts out with an episode of Probing the Membrane of Science with Professor Membrane. Professer Membrane starts out his episode with a question from the audiance. A kid tells him that his mom makes him eat breakfast chunks cerial for breakfast, but he hates them. He asks if he can go back in time and stop them from ever being invented. Professor Membrane tells him that altering the past to affect the present is possible. He tells him that he could prevent Walton Chunky to ever invent breakfast chunks by using temperal replacement technology. He gives a history of Walton working in a dump, and crushing cars. He has sack of bran right beside him, and that is where he gets the idea for breakfast chunks. Using space-time transfer device they replace a horrible giant squid into the past in replace of the bran. The giant squid eats Walton Chunky. Professor Membrane tells him that if breakfast chunks were never invented, breakfast squids would sweep the nation. He tells them that unpredictable effects may arise, like a giant fish in a bear suit. He tells them that anyone who creates a space-time transfer device is a complete moron.
Zim is watching this in his lab, and he's created a space-time tansfer device. GIR is playing around with a rubber piggy. Zim rewinds in the past where he sees Dib riding on his tricycle. He sees kids playing with an alien punching bag, and he says that he'll get the alien. Zim is about to send a Hunter Destroyer Machine into the past, and GIR tells him that if he sends the machine to destroy Dib in the past, then he won't be his enemy, then he won't have to send the machine to the past, but then Dib will still be his enemy, and he'll have to send the machine to destroy Dib, and GIRs head explodes. Zim sends the Hunter Destroyer Machine in, but it is spit back out because it is not compatable with Temporal Field. Zim gets mad and chucks GIRs rubber piggy at the portal, and the object is accepted.
Back in the past, Dib is riding to try and get the fake alien, but his tricycle is replaced by the rubber piggy, and he smashes into a tree.
At Dib's house, Dib starts yelling at Gaz for eating all of the cereal. In the middle of their arguement, Dib transforms in the way he would look if he had ran into a tree. He asks her if he's always sounded that funny, and if he's always had that claw for a hand. She reminds him about the tricycle accident he had, and he suddenly remembered. A commercial of Bloaty's Pizza Hog comes on, and Dib is haunted by the pig.
Zim is watching this, and he says the plan isn't as good as the Hunter Destroyer plan, but he might be able to rid himself of Dib. GIR is crying that he loved the piggy. In the news, Giant fish in bear suits are rampaging around Tokyo.
In the past, Dib is trying out Professor Membrane's hover helmet, to see if he can make it into space. He gets up pretty high. Zim makes GIR make him another piggy, and, back in the past, Dib's hover helmet is replaced by a rubber piggy. Dib falls from about a 2000 feet in the air, and he lands in the back yard, face down.
At Dib's house, Dib is wearing a cloacking jacket, and he tells Gaz he is going to spy on Zim. He's reading off how he' going to infiltrate his base, when his cloack is replaced, and he's wearing a breathing thing, and he is even more badly damaged than last time. Dib can hardly breath while talking to Gaz, and he asked Gaz if he's always had tubes in his neck. Gaz told him about the hover helmet accident, and said he punched a hole through the sewer system, and asked her if his plans had always been that lame, and he's always seeing pigs in his head.
At the lab, Zim is declaring more piggys. GIR gives him one, and he wants more. GIR opens his head, and it is raining piggys. Zim tells him they are for science, but GIR starts crying, and Zim lets him play in the pile of piggys.
In the past, Dib is climbing up a tower to get pictures of a big foot baby. The big foot kid tells him that he just wants to eat gurbs, and Dib tells him to eat his grubs, and the camera is replaced by a pig. Dib freaks out and falls off the tower.
Dib is walking to Zim's house, and in the process, he suddenly looks even more badly damaged. GIR is walking outside with a rubber piggy, and sees Dib. Dib screams, GIR screams, Dib screams again, GIR screams again, drops the piggy, and runs inside. Dib notices the pig. Zim is in his lab, and he hears Dib banging on the door. GIR is just watching him. Dib tells him that he knows it's him behind the rubber piggys, and that they have ruined his life. Zim is just sitting there laughing, because he's so close to victory.
In the past, after Dib falls off of the tower, the paramedics are using those things where they say clear, and they shock them, and those are replaced by two rubber piggys. Dib is now dead, and Zim relaxes with a nice cold Irken Poop. Zim goes upstairs, and while he is, Dib's lifeline starts back up again. On the TV in the past, Professor Membrane is talking. "Since my son's skeleton was accidentaly crushed in a paramedic freak piggy accident, I've created the new, Megaboy 3000, fusion power titanium exoskeleton. It will give him the strength of 10,000 little boys.
Zim comes up from his toilet elevator, drinking his Irken Poop, when Dib starts breaking the walls apart. He askes himself what went wrong, that last piggy should have reduced him to nothing, and he goes back into his lab. He starts screaming how his life has been nothing but a hideous pig filled ordeal, and that he can hide, but he cant... hide. Zim keeps throwing in more and more piggys, but this just gives Dib's exoskeleton more and more items, such as rockets. Dib fires rockets at GIR, and he runs down into the lab. There is only one left, and that is the one that GIR is holding. Zim screams, "no!", and GIR screams, "yah, we're doomed!". Dib is destroying everything, and Zim suddenly gets an idea. He's going to warn himself in the past to never use the time machine. He rewinds to where he was in the past, with the Hunter Destroyer Machine, and Zim writes on the piggy. Dib is about to destroy Zim, and Zim throws the pig into the portal. Dib is now outside of Zim's house. Dib is happy that he is back to the way he was, and the gnomes throw him out.
In the lab, GIR is talking to Zim about it's like nothing ever happened. He asked where the last piggy went, and Zim is standing there looking stupid, holding his brain. The piggy is inside his head, and it says, "Zim, don't use the time machine, love, Zim!"