user
Given a cartoon image and a caption. Caption: They seem too skinny for carb based life forms. Question: Generating an explanation of why this image/caption combination is funny. Answer: 
assistant
A play on the term "carb" and "carbon". People often remove carbohydrates like bread from their diets in order to lose weight; here, the aliens are carb based life forms because they are coming out of a toaster, and the people are surprised that they are so skinny. "carb-based" life forms is a play on "carbon-based" life forms, i.e., life like humans that is based off the carbon atom.