Prank Call of Cthulu (The Grim Adventures of Billy & Mandy)

"Prank Call of Cthulu" is the thirteenth episode in the fourth season of The Grim Adventures of Billy & Mandy.

Plot
When Billy and Irwin start making prank calls, everybody knows that Billy is behind the calls because every telephone has a caller ID. While Billy searches in Grim's trunk in the basement for something to defeat the caller ID, he finds a skull-shaped phone with no caller ID. Grim warns him to not use the phone, because it is used to call the ancient demon Cthulhu, whose sole appearance makes people go mad, and if awakened will cause the destruction of the world. Despite Grim's warning, Billy and Irwin use the phone anyway, and they are sucked into it by tentacles. After the commotion, Mandy and Grim go search for Billy, and they find themselves in a strange place with other tentacled creatures. In this place, Billy and Irwin have been hired as official prank callers and steadily turn into tentacled monsters.

Why It's Funny

 * 1) The prank calls Billy and Irwin do are hilarious to watch, along with Harold's quote "why didn't anyone tell me my butt was so big?", Grim burning himself with coffee, hot sauce, acid and rocket fuel, and many more!
 * 2) * Irwin even makes a reference to the Joe Mama jokes, which would later appear in the season 5 episode, "Goodbling and the Hip-Hop-opatamus".
 * 3) The design of Grim's Grim and Gladys action figures (which Grim had while taking a bath) look pretty decent.
 * 4) Some fourth-wall breaks as well, such as Mandy saying to Grim that "the Grim Adventures of Mandy doesn't sound as good as Billy & Mandy" when Grim says "the world is already doomed. Why can't we watch TV instead?", along with the narrator saying "to be continued..." and Billy saying "hey, what happened to my nose?"
 * 5) The monsters in the place the monster in the magic phone without caller ID also look decent, along with Billy having an octopus nose (depending on your view), and all the other people's monster forms. And the plot avoids coming across as a rip-off of Mh:greatestmovies:Monsters, Inc. and Aaahh! Real Monsters.
 * 6) The song the monsters sing after getting prank called is also very hilarious.
 * 7) A couple of yellow snakes tying a monster's shoelaces is very impressive.
 * 8) Decent Ending: When Grim smashed the magic phone with caller ID with a tennis racket, it turns all the monsters back to humans. Though Grim not answered when Mandy tried to ring him to get back to the house, Irwin says that she'll have no choice to go out with her and Mandy gives him a whack. And it ends with a monster playing golf with a black screen.
 * 9) "Say it! Don't spray it alright buddy!"
 * 10) 4th wall break: When Grim was telling Mandy that he knew what the monster said he tells her that's he is good at reading subtitles backwards.

Bad Qualities

 * 1) Plot Hole: How did Billy get from a country western place to Grim's bath in just three seconds?
 * 2) Depending on your view, Billy but with a monster nose and mouth looks rather messed up, and the stuff Billy was eating had a screaming face on it.
 * 3) The only gross-out bit was when a monster spits on Grim when he was prank calling him and Mandy.

Reception

 * It holds a rating of 8.1 out of 100 on IMDB.