Best "dumb" customer problem:
A rather irate customer who traveled maybe 30 miles, because another GameStop location informed him we had "tons" of Xbox 360 Pro bundles. We did have a couple, not "tons", as I told him and he was just like, "Well, you better have them, I traveled all this way for that Xbox 360!"
I asked a staff member to get a serial number sticker so we could ring up his purchase, and I repeated his order (I do this with all customers), that he wanted a Xbox 360 Pro bundle. That's when he starts off this bit of lunacy by telling me:
"Yeah, that's the 60GB one."
"Uh, there is no 60GB model. There is a 20GB model in the Pro Bundle, which you are about to purchase and a 120GB model which we are all out of stock."
"No, there's a 60GB model. I don't want that big one - it's not all the way backwards compatible."
"Oh, I think you're mixing it up with the PS3 - there was a 60GB PS3 model, which is obsolete and out of production. The 80GB model of the PS3 is pretty much backwards compatible with PS2 games and the 40GB is not."
"No, I know what I'm talking about - the Pro should have a 60GB hard drive! It used to have a 20GB HD but they don't make it anymore!"
"They never made a 60GB HD, but Sony used to make a 20GB PS3. Are you sure you don't want a PS3?"
"I know what fucking machine I fucking want man - and I want that 60GB Xbox-fucking-360! I traveled 30 miles for it and they said you have it!"
"Sir, we do have the Pro Bundle, but I'm sorry, it's only 20GB hard drive capacity!"
"Then I don't want it! If you won't sell me the right one, I will just go to Target or Best Buy!"
And he walked out angrily.