They are blue swim trunks that SpongeBob wears when at Goo Lagoon and contain a white elastic band. They appear to be rather fragile.
Role in series
When SpongeBob and Sandy are at Goo Lagoon, enjoying themselves, Larry walks up to the two and challenges them to a weight-lifting competition.
After SpongeBob exhibits a lack of strength from lifting a stick with two marshmallows, he fakes what the audience appears to interpret as actual power this time, only for him to rip his pants just before succeeding. This leads SpongeBob to blushing from embarrassment, but then finding it funny after the audience laughs at his mistake.
Throughout the episode, he annoys various Bikini Bottomites with "ripped pants" jokes, which they find hilarious. However, the joke shortly wears out after SpongeBob's overuse of it.
Later on, SpongeBob is shown inanimate on the shore of Goo Lagoon. This absolutely shocks the lifeguard, who immediately goes out of his way to save him. It is later revealed that nothing bad happened to SpongeBob and that he only faked his death for attention to tell a "ripped pants" joke once more. Although he thought it would he his funniest joke yet, everyone is disappointed in SpongeBob and abandons him as a result.
SpongeBob is ashamed of himself and tells his swim trunks that they blew it. The pants then come to life and ask in a French accent, "What do you mean we?" and run away. Upon going through this, he asks if he is the biggest loser on the beach, which leads three people to show sympathy to him and assuring SpongeBob otherwise.
After this instance, SpongeBob and the gang break into a song about how the overuse of the "ripped pants" joke affected the beach attendants, which attracts several listeners and results in his friends reconciling with him.
Despite having completely ripped apart in "Ripped Pants," SpongeBob is shown wearing his blue swim trunks once again in "Walking Small," "Bubble Buddy," and "SpongeGuard on Duty." Although the recovery is unexplained, it is most likely that he got them sewed or bought new ones in the same color.
SpongeBob rips his swim trunks a total of six times in "Ripped Pants."
In most other episodes that feature Goo Lagoon, SpongeBob wears red swim trunks rather than these.
There is a toy produced by that consists of a SpongeBob whose pants can rip.