"Make Room for Lisa" is the sixteenth episode of Season 10.
Lisa experiences stress when forced to temporarily share a room with Bart. Meanwhile, Marge discovers the joys of eavesdropping on cellular telephone calls and becomes obsessed with the personal dramas of complete strangers.
Homer, while at the Power Plant, becomes terrified that he hasn't warned everyone about Hitler when he believes that he somehow time-travelled to 1939 (thanks to a radio report). Carl and Lenny then "help Homer to the present" by changing the radio station (and imply that this happened before). Bill and Marty then proceed to announce a long celebration at P.J. O'Harrigan's. Lenny and Carl remark that work has to make them miss the party, but then discover that Homer managed to sneak out of work and arrive at O'Harrigan's for the party. Afterwards, Homer is passed out drunk after parking his car partially on the lawn and causing backed-up traffic on both lanes, revealing he had won the award of Sir Drinks-A-Lot. Marge then helps him inside to scrub the gum off his hair, although not before Homer drunkenly asks Marge what her favorite radio station was (obviously in reference to Bill and Marty).
The next day, Homer must take the kids on a family outing in order to bond with them as it was one of the Saturdays in the current month, and unfortunately for him Lisa gets to choose as Bart traded his turn for her dessert, which he did again when Homer punished him with no dessert. They visit a national treasure museum sponsored by a cell phone company, Omnitouch. While there, Homer accidentally damages the Bill of Rights and is forced to repay his debts. He does so by letting the Omnitouch company build a cell phone tower on their house. Lisa comes home from school to find that her room is gone and replaced with several machines to help power the tower. She becomes irritated with Homer.
Now that her room is gone, Lisa is forced to stay in Bart's room, where he purposely drives her crazy. After a while Lisa starts to get severe stomach aches caused by stress. Dr. Hibbert says he can give her harsh antacids, but feels that herbal tea might suit Lisa better. Lisa agrees until Homer buts in saying he won't let Lisa near the stuff and demands the antacids. After finally having too much of her father belittling everything she likes and believes, Lisa snaps at her him, claiming that just because he thinks what she likes is stupid and boring doesn't make that true. Seeing this manner Homer settles and says that they are just too different, and they will eventually grow apart. To get her cooled down, they visit a store run by a "hippie lady", who sells all different types of soothing items. She gives them some time in some isolation containers that will allow them to think. Lisa goes on a mental journey where she sees herself in the form of Snowball II and Homer where she realizes that Homer really does try to be a good father and takes her lots of places he hates. Homer, however, is not thinking and his container is taken away by repo men who aren't willing to wait 'months' for the hippie lady's lease to expire. His container falls off the truck and the Flanders find it, believe it is a coffin and bury it. The tank breaks though the ground and ends up in the ocean and washes up on a beach, where Ralph Wiggum reports it to his dad. They bring it back to the store where they get out and reunite. Lisa and Homer then go to the monster truck rally to spend time together.
Meanwhile, Marge starts hearing cell phone conversations over the baby monitor and starts using it for her own gossip gain. Bart and Milhouse plan to teach her a lesson by pretending to be robbers about to hide out in the house. When Milhouse opens the door, Marge smashes the baby monitor over his head. Having learned her lesson, she and Bart drag Milhouse's unconscious body inside and claim that "Bart hit him".