I've seen cels like the one above showing Daffy dancing with Porky pop up on various animation art dealer websites for years now, but was never quite sure where this scene originated. Thanks to YouTube, it appears it came from the opening to an Italian compilation television program titled Warner Show. The intro below suggests the show showcased the Looney Tunes and other popular WB animated shows of the day (Tiny Toons, Taz-Mania, Animaniacs).