user
Given a cartoon image and a caption. Caption: Take away the computers and they’re just sitting ducks. Question: Generating an explanation of why this image/caption combination is funny. Answer: 
assistant
A play on the phrase "sitting ducks" --- figuratively, sitting ducks are vulnerable people. The joke from the professor is that, if computers were taken away from their students, they would be incapable and vulnerable, a reference to dependence on technology. But, because the students are literally ducks, if you took the computers away, you would literally be left with a room full of ducks sitting down.