I had a prescription delivered via the mail-order pharmacy yesterday. It's much cheaper, inexplicably, to have it FedEx'd to me than to pick it up three blocks away... literally, $20 instead of $90.
But the invoice inside says, "Payment Due Upon Receipt."
Now, um, really? Because in Costa Rica, that means the guy will stand in your house till you pay him. Or, if he gets bored, he will leave and then send a courier service every single day (always at the MOST inconvenient time) to request payment until you DO pay. (Sometimes twice a day. Also, lots of phone calls.)
Somehow, I doubt they'll know if I put payment in the mail today, tomorrow or even - gasp - Tuesday!