user
Given a cartoon image and a caption. Caption: There's really nothing to it. Question: Generating an explanation of why this image/caption combination is funny. Answer: 
assistant
A play on the phrase "nothing to it" --- in the context of rock climbing, this phrase would usually mean that "there's no particular special skill required, it's easy to rock climb!" But, because there's literally no surface the person is rock climbing on, the climber is referring to the fact that he's literally climbing nothing.