I am NOT an unclear person.

I'm sitting at my computer reviewing sales. A woman comes up to me and asks, "Do you have 'Dreams of my Father' on tape? I don't know the author."
First of all, it's "Dreams FROM my Father" and if I weren't competent I wouldn't have been able to automatically know that, know that Barack wrote it, and locate it without any flustering about the difference between "of" and "from." Because sorry, but our computer isn't that smart.
But.
"It's actually not available in tape format, unfortunately," I say. "We do have it in CD, however."
"CD? What does that mean?"
My mouth opens and closes as I try to figure out how to explain this basic media format without sounding condescending.
"It's..a CD. Like a music one, but with a book on it?" I hate it when I talk like this, lifting the ends of my sentences as if I'm uncertain. It's the only way I can do this without sounding rude, because, as my bosses have noted, my voice is too flat otherwise.
"You mean they can listen to it in the car?" This woman peers down at me.
"Well, if they have a CD player they can..."
"But you said it wasn't available."
"I said it wasn't available on tape."
At this point I realize we're having a problem with semantics. Had she asked, "Do you have the book-on-tape version of ..." I would have probably assumed she was talking about audio books. But since she said, "Do you have...on tape" I thought she was specifically looking for it on tape.
"But it's on CD?"
"Yes, I'm sorry...I didn't realize you were looking for any audio version."
"Well, I asked for a book-on-tape." She's bitchy now, and this irritates me.
"But I told you that tapes aren't available...."
"It's a TERM. I didn't actually mean tape." She says this as if to imply that I am, in fact, retarded.
"I'm sorry," I say, my teeth grinding together. "I take things specifically and I thought you wanted a tape." SINCE YOU ASKED FOR ONE, SPECIFICALLY, I resist saying.
"Yeah, well, I obviously meant CD." She flounces away.
Well, I obviously meant to make your life more difficult by taking what you said at face value. Soooo sorry.
Haaaaaaaaaaaaate.