CPF in Brazil and purchases made online

This doesn't necessarily involve travel, but does in a way and is similar enough to other questions I thought I'd give it a try.

My best friend is trying to buy something through an online retailer, in Brazil, to be delivered to a resident of Brazil. In the purchase steps (through Google website translate), she's asked for a CPF (equivalent to an SSN or NIN).

We've tried phoning the company (they don't speak English, understandably, and her Portuguese is very limited). Can anyone explain why a florist might need this, and what the appropriate thing to do for someone who obviously doesn't have one to put in that field might be? (Leaving it blank causes a form validation error)

By all means, if there's a better stack for this, please let me know, but this was the closest I could come up with.