user
Given a cartoon image and a caption. Caption: He's his own best friend. Question: Generating an explanation of why this image/caption combination is funny. Answer: 
assistant
A play on the phrase "man's best friend." The dog throwing the stick to himself is doing so alone, and taking the role of a human owner who might otherwise throw the stick. So, instead of being "man's best friend", he is his own best friend, and he doesn't need humans.