What a Nightmare, Charlie Brown!1978

Charlie Brown:
[to Snoopy, who tries desperately to pull the sled] What in the world is the matter with you? Dogs in the Arctic don't behave like you do. In the Arctic, dogs are workers. They don't lead prima donna lives. They've got a chain from their collar that extends about eight feet. And unlike you, they're tied to a post or tree unless they're going to pull a sled. I guess I'll have to show you. Here, give me the harness [grabs the harness and puts it on] This is what you're supposed to do. You get into the sled, and I'll show you.