user
Given a cartoon image and a caption. Caption: Weren't there three of you? Question: Generating an explanation of why this image/caption combination is funny. Answer: 
assistant
A joke about the third diner falling off the roof. This odd restaurant has very few safety constraints, and has tables on the roof with no guards against falling. A waiter asking where a member of a dining party is is not unusual (e.g., if they want to wait to make sure everyone is there before taking orders), but here, it's because they fell to their death, as their dining partners looked on.