The Sludge Monster is an episode from the second season of Garfield and Friends.
After their car breaks down, Jon Arbuckle and his pets stay at a hotel for the night. Jon shares the tale of the Sludge Monster with his pets, who become paranoid as a result.
On a rainy night, Jon, Garfield and Odie are driving toward a lake for a fishing trip. Jon is confident he knows where he's going though Garfield tells Odie they are lost. Jon asks for the map and believes he knows where the lake is until Garfield tells him the lake is a blueberry jelly from his sandwich. Seeing this, Jon finally admits they are lost and hopes things will not get any worse.
Right after Jon has said that, a tire is blown and they stop right in front of an old hotel. When Jon goes into the back for a spare tire, it is revealed that Garfield took it out in order to make room for the hibachi. Knowing that the gas station they passed by will not open until morning, Jon states that they will spend the night at the hotel.
Once inside, Jon rings for service to which the hotel clerk pops up and alarms Jon and his pets. When Jon tells them they want to stay for the night, the clerk is delighted and tells an unseen figure named Maurice about their guests. Maurice then shows a room to where the three can stay much to the confusion of Jon. He asks if there are more guests in the hotel making the clerk laugh and closes the door hoping they will enjoy the night which frightens Garfield and Odie. Jon says as long as they are here for the night, they should make the best of it and goes to unpack his stuff while Garfield and Odie barricade the door.
While unpacking, Jon comes across a placard which talks about a folktale of the Sludge Monster. He then asks the pets if they know the Sludge Monster, to which they answer in the negative. He then goes into a song about the Sludge Monster, which makes the pets even more paranoid. Afterwards, Jon heads for bed, while Garfield and Odie are still paranoid. Later that night, while Jon is asleep, the two cannot sleep. Eventually Garfield realizes that the Sludge Monster is nothing more than fiction and they are paranoid over nothing. A gust of wind blows the shudder windows open and shut frighting the two. Thinking it is the Sludge Monster, the two try to stop it.
Heading down to the lobby, the two open the front door. Thinking that the Sludge Monster's out there, Garfield pushes Odie the door to check for the monster. This result in Odie landing in a puddle of mud and getting dirty while Garfield thinks the Sludge Monster got him. After barricading the door, Garfield fears that the monster would find a way into the hotel and attempts to leave. Odie whose still covered in mud managed to enter through the back door and Garfield flees from him and into the room.
Upon entering the room, he wakes Jon while Odie follows. Garfield jumps into the air and lands on the curtains with his claws, slowly falling to the floor. He is eventually cornered by what he thinks is the Sludge Monster. After getting licked and getting cleaned by Jon, he quickly realizes the Sludge Monster is actually Odie. Since he is awake and annoyed, Jon declares that they will head the gas station, and starts to pack.
Back at the lobby, the clerk tells him that they tried their best to enjoy their stay. Jon says the room was fine and it was his pets that messed everything up. As Jon leaves while lamenting to Garfield and Odie that they cannot behave, the clerk views this from the door enjoying their first customer in a year. He then wonders if they believed the story about a Sludge Monster and wonders why they cannot keep guests for long. Maurice, who appears out of thin air as a Sludge Monster, says they should get cable television, to which the clerk says "It's a start".
- The title card for this episode appears in "The Lasagna Zone".