You will Watch The Grim Adventures Of Billy and Mandy Season 4 Episode 9 online for free episodes with HQ / high quality. Stream cartoons The Grim Adventures Of Billy and Mandy Episode 48 Duck!: After Grim has a nice dream, a nightmare escapes the back of his head in the shape of a supernatural, invisible duck that makes farting noises. Then, the duck follows Grim everywhere, causing him embarrassment with the non-existent farts, and to end up in jail. Then, the duck repeats the strategy, following other citizens, including Irwin and Billy’s dad, resulting in all of them going to jail too. Finally, the duck tries to annoy Mandy, but she remains imperturbable by its presence, and eventually the duck disappears and Principal Goodvibes is really super angry to give mandy 75 days of detention.