|"Arthur's Cousin Catastrophe"|
|Number in season:||9b|
|Original Airdate:|| October 17, 1996|
|Written by:||Terence Taylor|
|Storyboard by:||Jean Charles Fink|
Arthur does his best to avoid his annoying cousin, Mo, at a family reunion.
Arthur's family was getting ready to host their annual family reunion, known as the "ANNUAL READ FAMILY REUNION". Just then, Arthur's Aunt Loretta, Uncle Bud, and three cousins: Monique (who usually goes by the name of "Mo"), Ricky, and Loretta's daughter form the family arrive at the front door.
Bud takes a picture of Arthur with his Supernova Solar Flash (a camera that X-rays people during the flash), and then Arthur politely welcomes them in. Loretta says that Mo has a surprise for Arthur and then Arthur remembers back in time for the past reunions: When Arthur was 5 years old, Mo started the trouble by putting him on a lawn sprinkler; when Arthur was 6 years old, Mo was doing judo on him; and when Arthur was 7 years old, Mo dressed him up as a baby by putting a bonnet on his head, a pacifier in his mouth, and a cloth diaper with a pin over his pants, and placing him in a pram, and everyone started laughing in front of him.
Arthur then screams and starts to run away from Mo, but Loretta states that Arthur has grown into an excitable boy. Outside, David starts the grill, but he doesn't have the burgers and hot dogs, but Jane does, and she walks over to the grill with the burgers and hot dogs and then takes over.
Arthur was hiding up in the tree to get away from Mo, whom he claimed was ruining his life. As Arthur gets down from the tree, Cousin George was about to show Arthur a comic book called SPIDERKIY, but Arthur starts running away as Mo is about to go near him, so George shows the comic book to Mo instead.
As Jane is grilling, Loretta walks to the grill and shows Jane the three-bladed spatula with a button, known as the Flip'omatic. As Loretta is demonstrating the Flip'omatic to Jane, she puts the three blades underneath the hamburgers, and then presses the button, but the hamburgers start flying way up high in the air, and Loretta admits she set it too high.
Meanwhile, outside at Mr. Haney's house, Mr. Haney starts going outside the front door for a wonderful day, but three hamburgers start landing on his head, and he brushes them off with his bare hand and runs back into the house.
While Jane and Loretta are still grilling, David announces a sack race. During the sack race, Arthur takes the lead and wins the race, but Ricky throws a fit for losing by throwing his cap off of his head and stomping on it while still in the sack.
Jane and Loretta continue lowering the notch of the Flip'omatic to get the hamburgers done. Then everyone starts eating dinner. Grandma Thora and her son-in-law Arthur's uncle are having a conversation with her mother (Arthur, D.W., and Kate's great-grandmother).
Then they start having an egg race, and Arthur's great-grandmother wins the race, while some others lose the egg before they reach the goal. Then they play charades, but it's hard when Uncle Sean picks an obscure book nobody else knows. Then David dresses as a clown and tells everyone it is time to play a game of musical shoes, but everyone was tired. A thunderstorm arrives, while it starts to rain very hard, and everyone gets back inside.
Later at night, Mo starts playing the piano, revealing that this was her surprise for Arthur, that she had taken up playing the instrument because she saw Arthur doing so. Arthur tutors her a little in piano basics, and Mo says the only reason she comes to these reunions is so she can see and play with him. They start playing a jazzy tune together, and then all their relatives come into the living room and dance along, and then David and Jane kiss each other. Uncle Bud mentions that despite the weather, this has been a great reunion, and we then see that the storm has cleared up with a full moon in the starry sky.
- Uncle Bud (debut)
- Loretta (debut)
- Jane Read
- D.W. Read
- Thora Read
- Thora's Mother (debut)
- Cousin George (debut)
- Uncle Sean (debut)
- Francis Haney
- Kate can be seen next to the table when Arthur views a wide angle of the yard through his binoculars. She is absent throughout the rest of the episode.
- In the flashback where Mo dressed Arthur up as a baby, the diaper disappeared in the later shot as the scene ends.
- The dormer window to the master bedroom is missing as shown in the top perspective shot when Loretta flips the hamburgers.
- When Arthur and Mo play the piano together, some of Arthur's fingers go through the keys.
- Spider Guy is a parody of Spider-Man.
- Musical Shoes is based on Musical Chairs.
- Main article: Arthur's Cousin Catastrophe/Gallery