He runs into a Krusty Krab support beam and begs its pardon. He then grabs the ketchup bottle that Plankton is hiding in and accidentally shoots him right through the wall of Mr. Krabs' office due to his bad aim.
Plankton appears inside his soda while he is spying on Mr. Krabs to find out that touching his thermostat triggers him. After 4 hours, Old Man Walker leaves the Krusty Krab bathroom after closing time and tries to exit but the doors were locked and he states he is locked in again.
He is shown eating with Incidental 87 at the Krusty Krab, with the latter narrating the amounts of chews he takes to finish his Krabby Patty and Walker demanding her to stop rushing him. They are eventually kicked out because of a deal made by the executive to sit at their table.
While SpongeBob is flooding the Krusty Krab with his tears, Old Man Walker floats on a barrel and says "I'm not a strong swimmer." He is also seen at the end of the episode, trying to find a nickel in order to use the restroom.
He helps SpongeBob's friends prepare for SpongeBob's surprise birthday party. Mr. Krabs has him keep watch for SpongeBob and alert everyone else when he arrives. However, when SpongeBob does arrive, he and Patrick send him zooming away on his walker, therefore, failing his given duty.
Patrick confiscates all of his sharp and pointy objects before entering the Bubble Zoo.
For the first ten seasons, he was credited as "old fish" or "old man." Several fans and episode 8 of Bikini Bottom Mysteries mistook his name as "Old Man Jenkins," who is a separate character. Season 11 began specifically calling him Old Man Walker; the credits for "Plankton Paranoia," "Pineapple RV," and "SpongeBob's Big Birthday Blowout" all use this name.
A running gag with this character is that he often appears in random places.