What's an "invoice" ?

[Doggett]

Is it like a bill or something ?
I was in a comic book shop and the owner was worried because he couldn't find one.
They must be pretty important things.

[Psycho Circus]

Yes, of sorts. Invoices can be for buyers or sellers, usually showing amounts paid or to be paid for a service or products. In terms of international sales, they show money paid, quantity of items included in an order and shipping costs. I work for the jobcentre and we recieve them from royal mail for sending letters and packets.

[Ash]

http://en.wikipedia.org/wiki/Invoice

[Raffine]

"Invoice" referes to the volume of speech mothers insist kids use whilst indoors.

"Stop shouting! Please use your invoice when you're in the den playing Clue, children!"