"Gus's Big Mouth" is the 79th episode of the series and the 1st(a) of Season 4 of Robotboy. In this episode, when Gus has a very bad breath Tommy and Robotboy take him to the dentist to clean his teeth's, unfortunately the dentist happens to be Felonious Hexx and gives Gus golden teeth which will make him say undesirable things to many different people.