Otto and Bart find the once high and mighty Truckasaurus in a junkyard and share dreams of its resurrected glory; Bart and Milhouse imagine themselves in an Itchy & Scratchy cartoon; Professor Frink returns with another lesson in weird science; and Bart enlists the help of a certain someone to get the best of Principal Skinner!
Riding on his skateboard, Bart comes across Otto working on a smoking school bus. Bart asks Otto how he can breathe with all the smoke coming from the engine. Otto says smoke doesn't bother him. Bart is hoping that the school bus won't be fixed and he won't be able to go to school tomorrow. Otto tells him not to get his hopes up because he can fix anything. They head to the Auto Graveyard to pick up some parts.
As Otto starts taking some parts off of an old bus, Bart finds the remains of Truckasaurus, "twenty tons and four stories of car-crunching, fire-breathing, prehistoric insanity." The junkyard owner says it's about to smashed into scap metal. Bart offers to buy it. The man says if he can get it off the lot, it's his.
Otto starts working on Truckasaurus. He's making progress but each time he rebuilds the engine, he ends up with more extra parts. He takes on to try to find out what it's for. Alone, Bart decides to check out the inside of Truckasaurus. Seeing all the buttons, he is tempted to press them all. He restrains himself and just pulls a lever. That causes Truckasaurus to come to life and walk out of the junkyard. Otto sees this and is bummed that he hasn't hooked up the brakes yet.
Truckasaurus begins smashing throught town. Soon the Springfield police arrive and Wiggum orders Bart to stop. He tells him that he can't stop it. Wiggum asks him then to try to steer clear of the bowling alley since it's league night. When Bart tries grabbing the steering wheel, it brakes off in his hands. Chief Wiggum tells him it's okay now because Truckasaurus is headed for Condemnation Alley. Bart is scared yet is having fun.
Wiggum notices that Truckasaurus is leaking oil. Bart manages to re-attach the steering wheel just as Hans Moleman is sending off the final payment on his car. The Mayor orders that the Air National Guard be called. Wiggum said he already did a half hour ago. Quimby goes to hide in his secret bunker.
The jets arrive. At first Bart thinks they're there to help him but then they shoot missles at him. Otto comes racing with the school bus and bumbs into Truckasaurus causing it to miss getting hit by the missles. Truckasaurus is now headed away from the city toward the water. Bart jumps out and swims to shore. Otto tells him he's going to get his wish. He won't be able to pick him up for school tomorrow. Bart wonders what he can do on a day off. Otto suggests they visit the Shelbyville dump to look for spare parts.
Professor Frink explains a prank involving a bowl of ice, an empty bottle, and a peeled hard-boiled egg. Placing the egg on the bottle causes it to get sucked inside by the cool air inside. He then places the bottle on a table next to a sign that says, "Free Egg."
Walking by, Bart sees the egg and figures it can help cut his costs on throwing things at nerds. He soon becomes frustrated that he can't get the egg out. He's about to smash the bottle when the Professor saves the bottle by putting his hand on the table Bart was going to use to smash it. Frink explains that he's been science pranked and all you have to do is blow into the bottle so that the air pressure causes the egg to come out.
Bart informs Frink that he already knew that. He snuck into the lab the day before and read his prank notes. Frink is surprised that Bart actually read something. Bart said with the word "prank," attached, he'd read anything. He has also set up his own experiment. There is a giant bottle in a bowl of ice. Frink comments that it is way too big for a normal egg when he gets sucked inside. Bart says he calls it, "Egghead in a Bottle."
Millhouse is over at the Simpsons and he and Bart are enjoying an episode of Itchy and Scratchy. Marge tells them that since it's such a nice day, she wants them to go outside. Bart is upset and has no idea what they can do. Millhouse suggests they play "Itchy and Scratchy" since they can't watch it. Envisioning himself as Itchy with a chainsaw, Bart calls dibs on Itchy. They go into the garage to see what Homer has left out for them to use. They find his toolbox, a crowbar, some gasoline, etc. Millhouse asks what the scenario could be. As Bart comes up with an idea, he pokes Millhouse in the chest to tell him his role. Millhouse runs out crying and Bart is left alone before they can do anything.
At a P.T.A meeting, Principal Skinner is receiving an award for his years of service from Superintendent Chalmers (despite his reluctance to do so). Just then, Bart swings by naked interrupting the ceremony. Chalmers, saying Skinner can't even control one student, takes the plaque and breaks it over his knee. Skinner informs Homer and Marge that Bart is expelled
The next day, Bart figures he's on Easy Street as he doesn't have to go to school or work like Lisa or Homer. Marge soon corrects him by saying that they are going to find a new school. They are soon turned down by every private school including General George Armstrong Custer Military Academy where they "massacre bad behavior." It seems Bart has been blacklisted by Skinner.
Bart decides to watch daytime tv and is soon bored miserably. He heads into town finding the place deserted (except for some tumbleweeds). Bart then enters the Kwik-E-Mart but is soon told to leave. Apu tells him they don't allow school children during school hours. Bart tells him he got expelled so he isn't a school child. Apu tells him they don't allow drop-outs either. Barney and Cleetus back up Apu saying only "respetable peoples" is allowed. Outside he is egged by Jimbo, Dolph, and Kearney. Bart tries telling them that he's like them now. They say that he's not. They're ditching school where as he was expelled.
Hiding in a dumpster, Bart soon sees Skinner's mom carrying a bag of groceries. He gets an idea and decides to try to help her. Thinking she's getting attacked, Agnes soon begins beating Bart with her bread. He is saved by an out-of-breathe Chief Wiggum and Officer Eddie. When she realizes that he's Bart Simpson, the little naked boy from the other night, she tells the police she'll deal with him. She thought it was funny but it also caused Skinner to lose a weeks vacation where they had plans to go on a singles cruise. She takes him home with her.
Skinner wants Bart out but Agnes says he's their guest and soon invites him to stay for dinner and parcheesi. After dinner, Skinner says he'll take Bart home. Agnes says it's too late and that he should stay over. Then she tells Bart to go upstairs and run her bath water. Seymour is upset because that's his job. Bart comes down in Seymour's pajama top and they end up having to share his bed.
The next day, Skinner is shocked that Bart is over again. Agnes tells him that Bart picked the drycleaning. The day after that, Bart is over and tells Skinner he's out of fruit juice. Skinner asks if he's going to be over all the time now. Bart says he doesn't have any where else to be. Skinner asks if he allows Bart back to school, will he stop coming over. Bart says that's fine with him. Bart and Agnes high five each other while Skinner thinks the got the better of Bart.