Uncle Tom's Bungalow, probably. Do I really need to say why? Personally, I thought the worst cartoons from '36 to '38 came from Friz Freleng. He directed a LOT of forgettable, one-shot music-based cartoons, a far cry from his more memorable and refined work after he returned to the studio in 1940. Tex's pre-Bugs work may not have been amazing overall but they were far better (and more true to the anarchic WB style) than Friz's during that time. Heck, "Porky the Wrestler", "Porky the Rain-maker", "Little Red Walking Hood", and "Daffy Duck in Hollywood" are some of my favorites.