Oh, I had one!
I wanted to make shelves to go in a cabinet in my old rental apartment. I was going to cover them in contact paper so they'd be vinyl coated. I discussed w/ my dad, and he said, "get the cheapest grade of 1/2-inch plywood and have them cut it."
So I went to the lumberyard and asked about plywood, and they told me I could get a 4'x8' piece of exterior-grade for $15. Great, I said, cut into two pieces 14inches by 12 inches.
The guy says, "But you have to pay us $1 a cut!"
I'm like, yes, I know, that's what, $3 or $4 more? fine. That's now about $18.
"No, you don't want this, you want pine board."
I argued with him, then when he kept insisting, I thought, OK, maybe he knows, and told him to write it up for pine.
So now he says, "But to get it 14" deep, you have to get clear pine, with no knots. And we'll have to charge you to cut it down, because it comes in either 12" or 16"."
The cost? $56, because clear pine is ex-pen-sive.
So, I'm like, "You know what, rip that up, and write down what I tell you. Plywood."
He's still arguing with me, and I say, "Why in the world would I want to pay $56 for lumber, instead of $15? I only want two stupid shelves, and I'm not going to paint or stain them, so I don't care what they look like."
"But you're buying a piece 4 by 8 feet. You'll have all that leftover wood!"
I said, "No I won't--you will. Do you think I'm taking it home? I'm going to take my two little pieces of wood that cost me $9 each, and go home. You can do whatever the heck you want to do with that plywood."
He's still arguing! and I'm getting louder. And a manager stops by, because he's been stuck with me so long. And the guy tries to explain to the manager, and I said again, "Why do I want to spend $56 instead of $18?"
The manager says, "cut her the plywood," and walks off.
So the guy writes it up and grumbles the whole time.