Sally and Peter goes to a restaurant near the office where they work. They decided to order something to drink, but something is wrong with Sally's drink. Let's check it out:

SALLY: Damn! My Coke is flat.

PETER: So why don't you complain to the waiter?

SALLY: Good idea! Hey waiter! Waiter! ...

It is really awful when our drink goes flat. FLAT describes a drink that stopped being fizzy. How about you? Do you like flat drinks? I don't think so.