Larry invites Sandy and SpongeBob to lift some weights, and they accept. Sandy and Larry start lifting weights, and Spongebob lifts a stick with two marshmallows on it to impress the crowd. He then rips his pants when lifting it.
SpongeBob uses Anchor Arms to look more muscular, and goes to Mussel Beach to show them off. Sandy decides to enroll him into the 8th Annual Anchor Toss. When its his turn to toss the anchor, his Anchor Arms explode, revealing that he was actually weak.
Mussel Beach is a pun and misspell on the word "muscle," with mussel being a type of shellfish.