The narrator explains that sometimes every day was a holiday for SpongeBob, even if he had to make one up. SpongeBob then wakes up with a Viking costume on, and exclaims "Hey everybody! It's Leif Ericson Day! Hinga Dinga Durgen!" He then goes outside to play with his friends, but finds notes at the houses of Patrick, Sandy and Squidward notifying that they can't play. He decides to make a new buddy, and after several failed attempts, creates a humanoid, happiest bubble named Bubble Buddy. The two go to the Krusty Krab, where SpongeBob orders everything on the menu for Bubble Buddy. However, SpongeBob explains several specifications that Squidward has to adhere to in order to satisfy Bubble Buddy's alleged preferences (lactose intolerant, etc.), making him remake the patties several times. After the meal, Bubble Buddy pays in "bubble-money" (which pops, and is feign money) and leaves a tip of "bubble coins" which also pops, making Squidward and Mr. Krabs mad.
SpongeBob and Bubble Buddy then go to the Goo Lagoon, where they continue to cause trouble, even resulting in the demise of one fish. Eventually, the Bikini Bottomites become fed up with Bubble Buddy and begin to riot, even tipping over the lifeguard tower. Squidward steps in and blames SpongeBob and the bubble he has created, causing the mob to direct their efforts towards popping Bubble Buddy. They surround SpongeBob and Bubble Buddy, brandishing sewing needles. SpongeBob tries to inform the crowd that Bubble Buddy is uncomfortable around their pointy needles, but they tell him that they are done with Bubble Buddy. SpongeBob tries to escape by inflating Bubble Buddy, but he flies weakly back into the crowd's grasp. SpongeBob says Bubble Buddy is his special friend and tries to ask if they ever had a special friend. Although some do reveal that they do have a special friend, it isn't enough to change their mind. So they throw SpongeBob out of the way. Squidward begins to stab Bubble Buddy, but he suddenly comes to life and catches the needle before it reaches him, much to the shock of Squidward and the other crowd members. Bubble Buddy then tells SpongeBob that "things are getting a little weird around here," and leaves in a bubble taxi, flipping into the sky, wishing SpongeBob a Happy Leif Erikson Day. Everyone appears to be OK with Bubble Buddy leaving Bikini Bottom except Squidward who is still shocked at what happened. The rest of the crowd then leave to go on with their regular lives and SpongeBob happily cries that people grow up so fast before leaving in a flurry of bubbles. All but one of them pop, and Squidward greets it.