[writing furiously] “Garbage in garbage can” …hmm, makes sense.

Let’s talk about garbage.

Common Subway Announcement: Help us keep the subway litter free. Please use trash receptacles.

Homer and Marge at “Family Skills” class (3F01):

         And put your garbage in a garbage can, people.  I can't stress
         that enough.  Don't just throw it out the window.
  Marge: This is so humiliating.
  Homer: [writing furiously] "Garbage in garbage can"...hmm, makes
         sense.