Above is the first sketch, where I had a vague idea involving Alice barging into Petey's room and annoying him with chatter. It was boring, so I gave her a puppet, which helped, but it didn't come alive until Beni joined her.
When in doubt for a big finish, introduce Dill. But I didn't know what he'd say until the very last minute. Above is the rough I sent my editor; you can see that I added the final comment outside the box. Then I moved it over to Dill's balloon, et voila.