Funny incident at Kragen Auto Parts

I haven't bought any trans fluid for a while. I asked the guy for some Dexron and he gave me Dexron/Mercon. Admittedley, I didn't know what Mercon is. So I asked him, are these the same? Or is there a fluid that is just Dexron. He copped an attitude, acted like I was the biggest idiot in the world, and proceeded to tell me how he is the expert, this is his business, etc.

Then he asked me what I was using it for. I told him I was going to put it in a Torqueflite 727. Then he asked, "Is that an airplane??"