The Koko (also called 'Ko-ko') cartoons from about 1919 to 1930 were amazing for their time and still are very enjoyable when seen today. In each, Koko the Clown (a cartoon character) ends up interacting with the real world...much like you saw decades later in "Who Framed Roger Rabbit".
When the story begins, Max Fleischer (Koko's animator) receives a letter. Apparently, it's for Koko and it is from his little brother who is soon arriving for a visit. When the little guy arrives, he and Koko try to outdo each other with acrobatics and later Koko is attacked by a kitten.
The animation is lovely. But the story really seemed wanting, as it really didn't look like they knew what to do in the cartoon once the brother arrived. Much much in the way of story.