Bob the Builder (1999)

S05E06 Muck's Monster

Title: Muck's Monster Plot: Wendy enlists Muck and Dizzy to help unclog a drainage system. While working, Muck becomes anxious due to the strange bubbling sounds emanating from the drain. To ease his nerves, Dizzy playfully suggests that a drain monster is lurking beneath the surface, heightening Muck's fears.