COD is not just a tasty fish

I got a call from a vendor this morning...

Her: *curtly* I'm calling about such-and-such a shipment. We haven't gotten paid for it. Can you tell me when to expect payment?

Me: Hmmm... that doesn't sound familiar. I don't think the invoice has come across my desk yet. Can you tell me when it was sent?

Her: According to UPS, it arrived at your store C.O.D. on December 2nd. So-and-so signed for it. When will we be receiving payment?

Me: You sent it C.O.D. with UPS?

Her: That's right. So, when can I expect a check?

Me: *blink* *blink* Well, if it was sent C.O.D., without knowing anything about it, I would have to assume that you've already been paid. It was delivered C.O.D. by UPS on the 2nd?

Her: *impatiently* Yes. I have the tracking record right here. So, you've sent a check?

Me: Noooo... UPS would have collected it upon delivery.

Her: What do you mean?

Me: Well, if it was sent C.O.D....

Her: That's right. Collect. On. Delivery. C.O.D.

Me: Yes. That's right. So we would have had to pay for it in order for UPS to deliver it. Collect. On. Delivery. C.O.D.

Her: Ma'am, I'm not seeing what that has to do with you sending me a check for the shipment.

Me: Well, if we paid for it when it was delivered, I don't want to send you another check and pay for it twice.

Her: Why would you have paid for it when it was delivered?

Me: Because, according to you, it was sent C.O.D.

Her: I don't understand. Hold on...

At this point I can hear her talking to someone in the background...

Her: Hey Gary, that thing was sent C.O.D., right?

Gary: Yup. What's the problem? When are they going to pay for it?

A different voice is heard in the background...

DV: Hey, you two! C.O.D. means that...*garbled sounds as the phone is now being covered*

Her: *back on the line* Uh, ma'am? I guess... the uhhh, shipment wasn't sent C.O.D. It was sent, uhhh... whatever the opposite of C.O.D is...