The Puzzling Letters

S3, E20: Beda writes an angry letter to Gustavsson because his shooting noise has scared her cow. When the postman wants to deliver the letter, he stops at Pettson and Findus' house first. Findus accidentally drops the letter into the soup, making it unreadable. The two trick the postman for a while so that he doesn't notice how they rewrite the letter on their own assumption about its contents.