If you've hung around me for long enough, you've probably heard me say "Back off! Get your own sandwich!" I then have turned to you and asked you if you remember that commercial. Inevitably, you haven't.
We used to say that all the time when I worked at Tim Hortons. Maybe it was a Nova Scotian thing? Anyway, I searched for a long time to find the commercial. I found it, and I present it to you now. Watch it a few times, and you'll find yourself saying "Back off! Get your own sandwich!" every so often. In fact, if anyone (including you) ever says "Back off!" you won't be able to help yourself from finishing with "Get your own sandwich!" any more than a toon can prevent himself with finishing the old "Shave and a haircut" with "two bits".