El Chewpoocaca debuted in the episode "Monster of Rock" when Kin and Kon told a Rock Lore about it. They told Corey and Laney that El Chewpoocaca was an evil sewer monster who kidnapped children while they went to the bathroom so that it could eat them. Laney didn't believe this story was true until they went down into the sewers and Kon woke it up with his burp causing it to chase after them. El Chewpoocaca went around kidnapping everybody including Kon. The band went off to search for it. They found Kon in a pot of stew getting cooked and all of the other people it kidnapped were trapped in a cage. El Chewpoocaca then captured Nick Mallory which gave Corey an idea on how to escape from it. He got the band to set the mood between El Chewpoocaca and Nick Mallory more like a date which made Trina jealous when she arrived and caused her to go into Diary Mode. Corey used the lyrics from her diary to play the song "Sweet Dreams," which made El Chewpoocaca go to sleep. Corey sealed it up in the sewer with bricks so that it would never come out again.
El Chewpoocaca is a big green slimy furry sewer monster with scales on its head. It has red eyes, thick black eyebrows, sharp white fangs, and gray pointed claws. El Chewpoocaca also has eyelashes that are visible at some times which may imply that it is a female.
- El Chewpoocaca is a parody on the mythical monster, El Chupacabra.
- Alternatively, its name could also be a reference to "Chewbacca" from Star Wars.
- It is possible that El Chewpoocaca may be female due to it wearing its hair in pigtails, revealing that it had eyelashes, and going on a date with Nick Mallory.