Role in the film
Anthony was looking forward to two things: passing his driver's test and to be able to drive Celia to the prom. While he was talking to her on the phone, Alexander had thought that he was talking nice to him. Due to misleading insults toward his "idiot brother", she hung up thinking that she was the one being insulted.
The next day, after Alexander's birthday "wish", Anthony ended up having a zit on his forehead. Ben had advised him to cover it up with a Band-Aid. At school, he managed to make it up with Celia by talking to her in the hall. Afterward, he got so excited that he jumped up, accidentally broke the school's trophy cases, and got sent to the principal.
Later on, while Anthony was taking his driver's test, he received a call from Celia. Ms. Suggs tested him about what was more important to him. When he chose to answer the phone, she ordered him to put it down. This causes him to accidentally drive recklessly and then fail the test. During a family argument, he first pinned the blame onto Alexander for his worst day ever.
By the time he picked up a teal suit, his parents had decided to be the ones to drive him and Celia to the prom. When she notices his outfit, she thought he looked like Willy Wonka. On their way to a Japanese restaurant, he kept silent as the others was making noises through their fists. At the restaurant, they sat far away from the others and she scolded him on how she hated those kind of restaurant. Upon seeing Ben embarrassing himself, Anthony and the others were kicking trash cans around and he realized that having a bad day with his loved ones makes it a good one. While Celia mentions that her unnamed friend were gonna offer them a ride together, he refuses, breaks up with her, and realized that the prom wasn't really worth it.
Back home, he notices that there was an Australian petting zoo for Alexander's 12th birthday and an alligator in the living room. He was last seen standing around in the backyard during the party.