Playing Dumb: An Untapped Genius

I stopped by the grocery store yesterday afternoon to grab a few quick items. I was there for milk, and Rob's "Crew" Pomade. On the way to the pomade, I saw some grapes that looked very tasty. I grabbed a bag and went on my way. Three items later, I found myself at the check-out stand. Just me, three items, and the checker.
He grabs the grapes and asks, "Wow. How do YOU know about these?" Baffled by the question, I answer, "They were just over in produce." "No," he responds, "how you you KNOW about these?" Hmm. same question, emphasis on different word - I still don't get it, so I stare at him blankly and say, "I just like grapes." I start searching through my bag for my wallet when he begins on being a cancer survivor. I think that is a fantastic accomplishment, so I tell him so, and continue to look through my bag. It's been a few minutes since I got there, and a line is starting to form behind me when he starts talking about how he was only cured by health foods. These grapes being one of his main sources of...this is where I start to fade out and look at magazines. I also notice that only ONE of my items has been scanned - and two are still sitting on the conveyor belt. I remember him saying something about writing a book next year, not being educated (but still smart), and starting his own Power Bar. He then drops the words Photosynthesis, Cranberries, Blueberries, Grapes, and says, "So you should only eat food that stains." Realizing that now is my chance, I say, "Oh - like Kool-Aid?" He scans my other two items, I pay - and I'm off.
I can only hope that as I walked away he thought, "Wow. That is the dumbest person alive."