- Larry the Lobster
- SpongeBob SquarePants
- Eugene H. Krabs
- Don the Whale
- Charlie (green)
- Mrs. Puff
- Debbie Rechid
- Frank (muscular goldfish)
- Vera Fishbowl
- Fred (blue)
- Old Man Jenkins
- Squidina's mother
- Taylor Fishbowl
- Nat Peterson
- Tina Fran
- Frankie Billy
- Abigail Marge
- Gary the Snail
- Frank (red shirt)
- King Neptune (mentioned)
- Bubble Bass (cameo)
- Harold Bill Reginald Scott
- Nathiel Waters
- Nancy Suzy Fish
- Squidward Tentacles
Synopsisgym to everyone in Bikini Bottom after seeing most are out of shape but at the price of a lifetime membership much to the displeasure of the crowd. However, Larry says that for only today, everything is free much to the excitement of the crowd who rushes inside of the gym. Customers sign in membership forms and Mr. Krabs suddenly appears upon hearing the word "free" from Larry who then rushes inside of the gym as well. Larry agrees to help anyone but sees SpongeBob struggling to open a door whom he tells it's automatic. SpongeBob isn't even heavy enough for the door to open and Larry assists SpongeBob inside. Larry then spots Mr. Krabs trying to leave with an exercise bike and reminds him the first visit is free. Mr. Krabs heads back inside mistakenly hearing that it will be forever free if he doesn't leave. Larry is eager to work out but must file out all of the membership forms first.
Inside, Larry is seen going through the paperwork and is worn out until SpongeBob walks up to him showing his cramps. Larry advises SpongeBob to always stay hydrated and gives him a bottle of water which SpongeBob drinks and his cramps heal. Larry then agrees to personally train SpongeBob but only if he signs a lifetime membership which he does (with some difficulty). Larry walks SpongeBob over to the exercise equipment and SpongeBob (after seeing Mr. Krabs barely lifting a large set of weights) starts to doubt himself saying he cannot lift weights. Larry, upon hearing this, puts cotton balls on a cotton swab to see if SpongeBob can lift it but SpongeBob wasn't able to lift it. SpongeBob continues to stay hydrated while Larry walks SpongeBob over to where he leads his exercise class the next day. Larry then decides to show SpongeBob some crunches but SpongeBob simply laughs as he doing this. Larry, who was in the middle of doing paperwork, is annoyed by Mr. Krabs flossing his towel in front of him saying "free towels." Mr. Krabs thanks Larry for the free membership and then leaves not before poking fun at Larry's potbelly as Larry is shown to be out of shape. Larry then enters the exercise room to check up on SpongeBob but is shocked by something.
The next day, at the Krusty Krab, the customers can be seen angry wanting their food, and in the kitchen, SpongeBob is seen very huge and muscular and is struggling with the Krabby Patties. Squidward is also surprised by SpongeBob's appearance and SpongeBob decides to leave back to the gym. SpongeBob arrives at the gym to see Larry completely out of shape. Larry comments saying he has been doing so much paperwork that he doesn't have any time to work out. Larry soon becomes depressed over his appearance with Mr. Krabs drinking his tears thinking it's "free soup." Later, SpongeBob is seen teaching Larry's exercise class demonstrating exercise procedures. Larry then walks over back to his desk barely even able to lift anything and SpongeBob eventually confronts him. Larry then decides to let SpongeBob run the gym but SpongeBob is sad that he's too big and strong to work the grill at the Krusty Krab. Larry and SpongeBob then share a "bro hug" and, suddenly, water pours out of SpongeBob and he returns to normal. Larry concludes that SpongeBob was overhydrated and that those were "water muscles." SpongeBob says that Larry's hug was strong enough to squeeze the water out of him. Larry then shares a laugh with SpongeBob while doing crutches and returns to normal. Back at the Krusty Krab later that evening, SpongeBob is excited to be working the grill again and Squidward comments that the day was even better as Mr. Krabs never showed up. At Larry's gym, Larry opens the steam room to find Mr. Krabs cooked up. Mr. Krabs then asks Larry if he could rub butter on him.
Adam Paloian, storyboard artist shared on his tumblr page there was a scene on this episode that got censored. "Here is a deleted/changed scene that didn't make it past the censors. In this scene, Larry originally said "The only thing worse than donuts is ground glass!" as he forcefully broke a glass cup in a fish incidental's mouth... Hmm, I guess now it kinda makes sense why S&P didn't approve of this one."
The scene sequence that got censored.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Surf Happy Fun (Underscore) - Billy Lincoln [Grand opening of Larry's gym.]
‣ Sea Shanty Medley - Phil Green [Krabs appears.]
‣ Roundup - Sam Spence ["In conclusion, I'm at your service..."]
• Hot Steel and Slide Licks (o) - Jeremy Wakefield [SpongeBob struggling to open the door.]
‣ Harp Ding - Nicolas Carr [Door opens.]
‣ Salty Krab Jig - Michael Bolger, Nicolas Carr [Krabs stealing a workout machine.]
• Hot Steel and Slide Licks (h) - Jeremy Wakefield ["...right after I file this paperwork"]
‣ Vibe Sting - Nicolas Carr ["Even your cramps have cramps!"]
‣ Surfing Sponge - Nicolas Carr, Barry Anthony ["Always be hydrating"]
‣ Nude Sting - Nicolas Carr [Huge pile of paperwork.]
‣ Regal Happy Theme - Sam Spence [SpongeBob filling out paperwork.]
‣ Sailor's Sting 22 - Michael Bolger, Nicolas Carr [Krabs lifting weights.]
‣ 12th Street Rag 3 with Bass - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Flashback.]
‣ A Fishy Conversation - Barry Anthony [Cotton swabs.]
• Hot Steel and Slide Licks (e) - Jeremy Wakefield [SpongeBob's arms break.]
‣ Beach Party - Harry Bluestone [Doing crunches.]
• Hot Steel and Slide Licks (k) - Jeremy Wakefield [SpongeBob laughs while he's doing crunches.]
‣ Sailor's Sting 22 - Michael Bolger, Nicolas Carr ["Free towels, free towels, free towels..."]
‣ Vibe Q Sting - Nicolas Carr ["Pot...belly?"]
‣ Evil Mind 3 - Dick De Benedictis ["Oh, my Neptune!"]
‣ Harry the Hippo - Phil Green [At the Krusty Krab.]
‣ What's This Sting - Nicolas Carr ["Larry?"]
‣ Pacific Blue - Tony Osborne [Larry says he's too busy to exercise.]
• Hot Steel and Slide Licks (i) - Jeremy Wakefield [Larry cries.]
‣ Earl's Revenge - Sage Guyton, Jeremy Wakefield [Exercise class.]
‣ M'Wanna - Sage Guyton, Jeremy Wakefield [Larry's sad.]
‣ Saltwater Works - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Larry asks SpongeBob to take over.]
‣ Vibe Sting - Nicolas Carr ["What happened?"]
‣ Roundup - Sam Spence [SpongeBob and Larry doing crunches.]
• Hot Steel and Slide Licks (e) - Jeremy Wakefield [The very next evening...]
‣ Another Krusty Krab Day - Michael Bolger, Nicolas Carr [Closing time at the Krusty Krab.]
‣ Vibe Q Sting - Nicolas Carr ["Huh?"]
‣ Dramatic Impact 6 - Ivor Slaney ["Mr. Krabs, how long have you been in there?"]
• Hot Steel and Slide Licks (b) - Jeremy Wakefield [Ending.]
- This episode is available on the SpongeBob LongPants, Complete Ninth Season, and Next 100 Episodes DVDs.
- This episode premiered ten years after Nicktoons Winners Cup Racing was released and six years after "Back to the Past" and "The Bad Guy Club for Villains" premiered.
- This is the second episode to end with Mr. Krabs being cooked up. The first is "Wishing You Well."
- This episode marks the fifth instance of SpongeBob being muscular. The first is "MuscleBob BuffPants" during a dream sequence and when he orders Anchor Arms, the second time is "The Fry Cook Games," the third is "Blackened Sponge" when he is dreaming, and the fourth is The SpongeBob Movie: Sponge Out of Water when he transforms into Invincibubble.
- The title card background for this episode is similar to that of "MuscleBob BuffPants," except that this title card is lighter in color and only has one dumbbell instead of eleven.
- This episode reveals that SpongeBob is stronger when he is filled with water.
- This episode marks Lloyd-Rich's first speaking appearance.
- Larry's shorts are blue and turquoise in this episode, while they are green and orange in other episodes.
- This is Larry's first major role in an episode since "A Life in a Day."
- This is also possibly his most major role aside from "Larry the Floor Manager."
- Irony: The front door of Larry's Gym is automatic even though gyms are supposed to promote exercise.
- "My leg!:" Frankie Billy screams this when he gets hit by the grill.
- SpongeBob says that he's too big to work the grill even though he is shown doing just that in his dream in "MuscleBob BuffPants."
- This is the second time a time card goes before in time instead of after in time. The first is "License to Milkshake."
- This episode supposedly premiered on Annoy Squidward Day (if the date of the holiday is correct).
- Larry's Gym reappears in "The Nitwitting" but as a generic gym, missing the anchor sign.
- This is the first episode of Bubble Bass as a recurring character after his retirement for 12 years after Season 1, except for one cameo in the Season 8 episode, "Plankton's Good Eye."
- Larry's Gym is a parody of Gold's Gym. The episode title card even uses the same font as the Gold's Gym logo.
- A poster on Larry's Gym's wall shows "No slacking" with Larry posing similarly to Uncle Sam. The poster itself with its purpose, however, is more similar to the "Big Brother is Watching You" poster.
- In the episode, it is established that SpongeBob can't lift up lightweight objects. However, other episodes (like "Wet Painters") show him holding heavier objects.
- SpongeBob often contradicts himself because he is able to hold a pencil, clipboard, and other things, whereas when Larry is pushing him, SpongeBob can't even lift cotton balls.
- The narrator says "The Very Next Evening" when the time card says "The Next Evening".
- Mr. Krabs commenting on the free service at Larry's Gym then calling Larry a "sucker."