Role in the film
Alexander doesn't exactly have an easy life, as he always has bad days every day.
After waking up with gum in his hair, he gets an e-mail about his friend Phillip Parker's expensive birthday being on the same day as his. He tells his family that he can't compete, but they don't listen. On his way to school, a boy is seen photoshopping Alexander's face onto the bodies of women in photos, and then posting them online.
By the time he gets to school, not only is he humiliated, but he learns that his best friend, Paul, is going to Phillip's party. He tries to ask his school crush, Becky Gibson, but she refuses as well. Afterwards, he accidentally burns down the periodic table with her notebook and gets blamed for it. While waiting for a long time outside of school, Alexander is put in charge of Mel, the class guinea pig.
Later that night, Alexander tries to talk to his older brother, Anthony, about his bad luck. While Alexander thinks that Anthony loves him as a brother, he is actually talking to his girlfriend, Celia, on the phone. While Anthony is talking to Alexander, Celia, thinking that he is trash-talking to her, abruptly hangs up, and Alexander hears Anthony calling him an "idiot brother". At midnight, he makes himself a birthday sundae and wishes that his family would see what it was like to have a "terrible, horrible, no good, very bad day".
The next day, he sees that his older sister, Emily, has a cold, and then wakes up his parents, who are oversleeping. As he leaves the bathroom, Anthony comes in, and reacts in horror when he looks in the mirror and sees a zit on his forehead.
At school, Alexander hears from Paul that Phillip's birthday party was cancelled, as he has the chicken pox, which meant that Alexander's is back on ("His pox is your gain"). Becky even mentions showing up. Alexander even hears that her brother, Elliot, who made the mean photoshops about him, has gotten suspended.
Throughout the day, while convincing them that their bad luck is his fault, Alexander learns that his baby brother, Trevor, got green ink all over his face. The Coopers later see Anthony accidentally trashing their van, which results in him failing his driving test. Emily gets drunk due to drinking too much cough syrup and ruins the Peter Pan play.
By the time the Coopers picks Celia up for the prom, most of them are playing music into their fists with their mouths. At Nagamaki, Alexander sees his father, Ben, catching food into his mouth eight times in a row, and then accidentally setting his sleeves on fire (which he puts out in a lobster tank). While Ben walks out feeling disappointed (and trying to hide it), Alexander follows, along with the rest of the family. After realizing that they got to spend the worst day together, they began kicking trash cans around.
After getting home, the Coopers discover a alligator in their living room. In the backyard, Alexander discovers that his parents have rented an Australian petting zoo for his birthday party. During it, he learns that Paul and Becky have shown up. During the closing credits, they are seen pretending to surf.
- Alexander appears to be fond of Australia, as he has Australian stuff in his room. He is also seen eating a spread that was originally made there.
- This could be a reference to two things: The fact that throughout the book the movie is based on repeatedly drops the line "I'm going to Australia" and also how Alexander's actor, Ed Oxenbould, is an Australia native himself.