Scam?

I was just witness to a foiled scam. Or to an adult man woefully unfamiliar with the ways of modern commerce. I haven't figured out which yet.
   I went to the grocery store, stocked up on fruit and yogurt and picked out a package of the Holiday Oreos.* My minimal needs met I moseyed up to the checkout stand.
   The guy in front of me was buying regular groceries - nothing crazy like a barbeque or ninety pounds of meat - nothing odd, nothing out of place. His total came to $39 and change.
   Here's where it gets weird. The guy leans in to the cashier and whispers something. She doesn't understand him so he has to repeat himself. Twice.
   He wants an $80 grocery gift card. Nothing unusual there, the cards are in easy reach of the cashier. But... he wants to pay for the groceries with the card. And then use the balance to buy gasoline, which this grocery store also offers.
   He has not yet purchased the card.
   The cashier rings up his purchase, which now comes out to $118, including the $80 gift card. The man starts to become upset. He wants to pay for his $39 of groceries out of the $80 gift card. He does not want to see $118 on the register. And he does not want to pay for the $39 in groceries with the $50 cash in his hand, for some reason. He wants to buy an $80 gift card and pay for the groceries with that.
   The cashier is confused, but not so confused she just does what he asks. She calls over a supervisor, who cuts to the heart of the matter. The man cannot pay for groceries with a gift card he has not yet purchased.
   At this point the man is upset, though not outraged or even very vocal. The supervisor offers to let him pay for the card first, then he can pay for the groceries once the transaction for the card has gone through. Seems reasonable enough to me, and it seems to be what the man actually wants to do, but by this point he's had enough. He says he doesn't want any of it and storms out, groceries un-bought.

Hmmm...

   This man was easily my age, which means he's been buying things at cash registers for well over half his life. I find it hard to believe that he wouldn't get the concept that you have to pay for the gift card first, then pay for your groceries with it. So I'm leaning towards scam.
   Yet the optimist in me wants to believe that he just wasn't getting his point across, and when he couldn't explain himself he got frustrated and left. Without the groceries he had shopped for and put through the checkout. And without paying with the cash in his hand.

I think it was a scam, averted by a cashier who refused to be taken in. And yet, you kind of have to admire the guy, trying to get away with something like that in middle of the afternoon. I wonder if this was his first time, or if he's done this kind of thing many times before.



* the creme middle is red, for Christmas. And for one of the days of Kwanzaa, I'm pretty sure.