The Grim Adventures of Billy and Mandy - Season 6 - Eps 20: Goodbling and the Hip-Hop-Opotamus
At a school fair, Grim's scythe accidentally transforms the dull Principal Goodvibes and his hippopotamus into gangster rappers, Goodvibes now calling himself Principal Goodbling. In the following, Goodbling changes the entire school to be more hip-hop-oriented, to the annoyance of Mandy. Although initially Grim likes the new style of the school principal, he later thinks Goodbling is just a poseur and goes to talk to him, but Goodbling attacks with yo-mama jokes. Irwin's grandmother, Tanya, confronts Goodbling and proves to be better than he is at yo-mama jokes that Goodbling reverts to being the boring Goodvibes.
About The Grim Adventures of Billy and Mandy

Title: The Grim Adventures of Billy and Mandy
First Air Date: 2001-08-24
Last Air Date: 2007-11-09
Status: Ended
Rating: 8.045/10 (from 958 votes)
Language: EN
Seasons: 8
Total Episodes: 184
Network: Cartoon Network
Genres: Animation, Comedy, Kids
Production Companies: Cartoon Network Studios
Synopsis
The exploits of the Grim Reaper, who has been forced into being the best friend of two children. A spin-off of the show Grim & Evil.
Cast

Greg Eagles
Grim (voice)

Richard Steven Horvitz
Billy (voice)

Grey DeLisle
Mandy (voice)

Vanessa Marshall
Irwin (voice)