Unable to get out of a mis-scheduled spring vacation, Principal Skinner makes up the holiday "Go to Work with Your Parents Day," giving Lisa the chance to spend time with Homer, and Bart the chance to work with Patty & Selma at the DMV. When Bart makes his own fake driver's license and Martin wins a bundle at the stock market, Bart rents a car, and takes Milhouse, Martin, and Nelson Muntz on a huge road trip.
- Having booked a vacation flight that he can't get out of without paying a large fee, Principal Skinner creates "Go to Work with Your Parents Day."
While Lisa goes to the Nuclear Plant with Homer, Bart assumes he'll be sitting pretty by staying home. However, the rules state that 'homemaking is not a work occupation,' and Bart is sent to be with Patty and Selma at the DMV.
During a lull while Patty gets several licenses laminated, Bart takes the opportunity to create a fake license (unlaminated and unsigned though). Using it, he, Nelson, Milhouse, and Martin partake in all sorts of over-21 goodness.
Eventually, they end up being able to rent a car, and go on a road trip, under the pretense that they are going to a 'National Grammar Rodeo' in Canada. The lie seems to work on everyone, except Lisa.
Meanwhile, Lisa has found that her time with Homer is actually fun, and they end up doing lots of activities at the Power Plant.
With the others gone, Marge finds her life to be very boring with little to do.
Eventually on the road trip, Milhouse questions just where they are going, leading to a conversation. Looking at a brochure in the car's glovebox, they find out about a World's Fair in Knoxville, Tennessee, and decide to go there.
However, upon arriving, they find that the fair was actually in 1982. The last of their money is spent on wigs (from an outlet store in the fair's 'Sunsphere,' now called 'the Wigsphere'), and an Al Gore doll. Upset at what has transpired, Nelson throws a rock at the Sunsphere, and it collapses on their car, stranding them in Knoxville.
With no other options, Bart calls home and talks to Lisa, confessing what happened and where they are, as well as asking how they can find some way to get home. Lisa suggests that Bart become a courier. This leads him to making all sorts of deliveries around the world, but does not get him any closer to getting home. Bart claims he needs to find something that can be shipped to Springfield, and be big enough to also fit Nelson, Milhouse, and Martin.
This preoccupies Lisa's thoughts as she visits Homer at the plant. Upon seeing her upset, Homer asks Lisa to explain what's wrong, and upon him promising not to tell anyone, she lays out everything that Bart has done.
Homer is at first upset, but then decides to help. Noting the size of the control console at his workstation, the two figure they can get the courier service to deliver a new one to the Power Plant. After spilling soda on the console, Homer makes a call for a replacement, and the boys make it home.
At the dinner table, Bart continues his lie about the grammar rodeo, as Lisa and Homer look on angrily...but Marge smiles politely, unaware of just what happened.
Later that evening, several phone calls are received: one from Principal Skinner asking if Bart has ever been to Asia, another telling of a smashed rental car under the Sunsphere, and a request for Bart to deliver a human kidney to Amsterdam.
Nearby, Homer quietly chuckles.