Here's Larson talking about that:

Transcript:
In my hometown, The Far Side is carried by the Seattle Times, which "crops" the cartoon so that it fits a little better on their comic page.
On the day this cartoon was published, friends started calling me for an explanation as to its meaning. I hadn't seen the cartoon myself (other than when I had drawn and submitted it weeks before) and the conversations sort of went in circles before I got a few clues that something was amiss
I opened the newspaper to the comic section and discovered that someone, in order to compress the cartoon's size, had chopped off a rather vital part of the humor.
The newspaper ran a correction the following day but, all in all, it's sort of nice for a change when no one understands one of my cartoons but it's not my fault.






It was Ratatouille