You will Watch The Grim Adventures Of Billy and Mandy Season 5 Episode 6 online for free episodes with HQ / high quality. Stream cartoons The Grim Adventures Of Billy and Mandy Episode 58 When Billy and Irwin start making prank calls, everybody knows that Billy is behind the calls because every telephone has a caller ID. Then, 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. Then, Grim warns him to not use the phone, because it is used to call the ancient demon Cthulu, 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.