While the Springfield Isotopes are mentioned in a few episodes, this specific design is from episode 11 in season 10 called “Wild Barts can”t be Broken”. In short, Homer’s drinking crew gets drunk celebrating the Isotopes and leave a path of destruction through the town. This gets blamed on the Springfield kids and a curfew is put into effect. This is near the end of the golden era, so it’s debatable whether it’s a good episode or not, but it does have some good jokes. I also noticed I forgot to put the text at an angle but now I’m too lazy too fix it. Meh.

Here’s the link to the product as a sticker, but you can view the design on multiple items if you’re interested.