As every day is a holiday for SpongeBob, he wakes up wearing a Viking costume and proclaims it to be Leif Ericson Day. He then goes outside to celebrate with his friends, but finds notes at the houses of Patrick, Sandy, and Squidward notifying that they cannot, or will not, play with him. SpongeBob decides to, literally, make a new friend, and after several failed attempts, he blows a bubble figure whom he names Bubble Buddy.
The two go to the Krusty Krab, where SpongeBob orders everything on the menu for Bubble Buddy. However, SpongeBob makes several specifications on Bubble Buddy's behalf that Squidward is forced to bend over backward to accommodate. After the meal, Bubble Buddy pays with "bubble-money," which quickly pops and infuriates Squidward and Mr. Krabs.
SpongeBob and Bubble Buddy next go to the Goo Lagoon, where they continue to cause trouble with their benign antics: holding up the restroom, causing misunderstandings, and leaving one fish to face high tide. Eventually, the beach-goers become fed up 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 and chanting their intent to pop the bubble. SpongeBob tries to escape by inflating Bubble Buddy, but he fails to fly away from the crowd's grasp. SpongeBob implores them to realize that Bubble Buddy is his special friend, prompting the crowd to remember similar friends of their own.
Unfortunately, this is not enough to change their minds. As the crowd knocks SpongeBob out of the way, Squidward brings down his needle. All of a sudden, Bubble Buddy comes to life and catches Squidward's arm before the needle reaches him, much to the shock of everyone except SpongeBob. Bubble Buddy informs SpongeBob that "things are getting a little weird around here," and departs in a bubble taxi, floating into the sky and wishing SpongeBob a Happy Leif Erikson Day. The majority of the crowd, satisfied, leaves to go on with their lives. SpongeBob happily cries for his friend blowing up so fast before leaving in a flurry of bubbles. All but one of them pop, and Squidward, left behind in a daze, awkwardly greets it.