Mr. Bleakman's Special Day Clifford the Big Red Dog : Season 1 Episode 60

Mr. Bleakman appears to the dogs to be particularly grumpy one day. At first they are upset with him, but then they overhear Mrs. Howard say that sometimes a grumpy attitude can be changed through acts of kindness. This inspires the dogs to perform a series of "secret good deeds" to see if they can turn Mr. Bleakman's frown into a smile. They are surprised to learn that performing kind acts makes them feel much better too!