I remember the first time I saw this comic, sometime in the nineties, I think. My dad explained it to me very similarly to how you did here.
There was a similar comic, which currently I can't find; I don't even remember if it was Far Side, but the art style in my head matches. The comic in question features two dogs hopping around a hillside covered in blueberries with one declaring to the other "you were right! This is thrilling!" I read them far enough apart in time that I think my dad had to explain it to me again.
Boxcar Willie. I read a pulp book series about travel between universes where they took the popular stuff on one world and hocked it on another. That was the reason that boxcar wilie albums existed.