"Wonder Bread" is the famous product of a company in America. When used with the word "account" this is the kind of thing an advertiser would say when talking about a client's advertising campaign. For example, they might say "Have you seen the latest commercial for the Wonder Bread account?".
The sentence structure you gave is a joke. The "Wonder Bread account" is the punch line. The reason for this is because the company that makes "Wonder bread" is very big, and worth a lot of money, much more than 20 million dollars. When compared to 20 million dollars, to not have the "Wonder Bread account" would be bad news, because that means that this is a loss of a lot of money.
This a cultural reference joke, because you need to know about "Wonder Bread", and every kid in America grew up on "Wonder Bread".