Lil is invited to a party with all of the popular kids from school provided her brother does not come with her as the kids believe he is socially inept and hygenically changed. Lil begins to pull away from Phil even though he tries to remain close to her. When Phil and Lil are partnered together for a science project. Lil freaks out and angrilly reminds everyone that she and Phil are seperate individuals and not a single person much to Phil's embarrasment. When their parents Betty and Howard arrive home excited for their family vacation trio Nick & Dick's Twin Canyon Resort Lil refuses to go. Betty upset that Lil is unhappy allows Lil to move into the family's office/workout room to give her a space of her own. However Phil struggles to deal with the changes and misses having Lil in his life despite Dil's attempts to become Phil's new twin. When Lil goes to her party her new friends begin to make fun of Phil which makes Lil realise how close to her brother she really is and she leaves the party after telling off the popular kids. In the end she agrees to go to the Twin's Canyon with Phil.
Meanwhile Chuckie struggles to complete the President Fitness Test and resents the embarrasment of gym class. The next day Chuckie refuses to attend gym class (by pretending to be sick) to take a stand against the President Fitness Test despite Tommy's objections. The day after that Chuckie hides out in the boy's bathroom but breaks one of the pipes in an attempt to see out the window. The bathroom becomes flooded but Chuckie is able to hold the pipes together for over and hour which impresses Panghorn however he still expects Chuckie to take the test in a few days.