His initial reaction is just to stare and try to parse what's happening right in front of him, or what kind of life this guy must lead to have these kinds of hysterical reactions so often. Little does he know that the same thing is happening in reverse, just with regards to his own straight-laced manner.

He does not back up, refusing to give ground in his own shop, thank you very much.

"... No. I don't have any friends." Not really. "I'm just trying to figure out what exactly you're planning on buying here so I don't have to keep ringing it up again and again. You don't want the card, I'm guessing?"