Curly's dream is to become the Ball Monitor, but when that duty is mistakenly handed to Sid, Curly snaps, steals the school's kickballs and locks himself in Principal Wartz's office.
The episode opens with Curly offering to help Arnold carry a bag of kickballs back inside on his last day as Ball Monitor. He makes several strange remarks about how much respect Arnold must have gotten while being Ball Monitor, which Arnold mostly ignores.
It is revealed that Curly is supposed to be the next Ball Monitor and he fantasises about what the day will be like until the announcement, deciding that he will be kind to his classmates to gain their respect. However, when it comes time to announce the week's Ball Monitor, Mr Simmons calls out Sid's name instead. Curly attempts to tell him that he made a mistake but Simmons believes that he is just upset that it is not his turn. In retaliation, Curly waits until the students go back to class and steals the bag of kickballs from the equipment cupboard, locking himself into Principal Wartz's office with them.
Curly begins throwing kickballs at the teachers and students from inside the room and using the school's loudspeaker system to rant about the 'injustice' he has suffered through the day, blaming the students unjustly for things he allowed them to do: Curly claims his classmates treated him like the doorman when he actually held the classroom door open for them, states that Harold 'stole' a question from him in class despite allowing Harold to answer it - which even Mr Simmons points out to him - and says that Sid cut the line at the drinking fountain although he moved out of the way for him. Sid offers to let him take over as Ball Monitor but Curly tells him, "I don't want your Ball Monitor week! I wanted my own!" and begins throwing more kickballs.
Mr Simmons and Principal Wartz both attempt to talk Curly down but are unsuccessful. He eventually demands two Yahoo sodas and a meatball sub but says he will only let someone he trusts deliver it: Arnold. Wartz plans to use this as an opportunity to take him out of the room by force but when Arnold brings the tray to him, Curly drags him into the room with him, with Stinky declaring that it is now a hostage situation.
Arnold manages to convince Curly to talk to Mr Simmons if he really believes he was supposed to be the Ball Monitor and they discover that he made a mistake on his calendar: the children had a week's holiday and he forgot to carry the names over to when they returned. They come to an agreement that Sid will finish up his week as Ball Monitor and Curly can have a full week the next week but Wartz still drags him away and assigns him a week's worth of after-school detention when they finally get him out of his office. The episode ends with Curly screaming that he can't have detention because he is the Ball Monitor and making barking and growling noises, presumably at Wartz.