“Can we be the Anti-Umbridge League?” said Angelina hopefully.

“Or the Ministry of Magic Are Morons Group?” suggested Fred.

“I was thinking,” said Hermione, frowning at Fred, “more of a name that didn’t tell everyone what we’re up to, so we can refer to it safely outside meetings.”

“The Defense Association?” said Cho.  “The D.A. for short, so nobody knows what we’re talking about?”

“Yeah, the D.A.’s good,” said Ginny.  “Only let’s make it stand for Dumbledore’s Army because that’s the Ministry’s worst fear, isn’t it?”

Harry Potter and the Order of the Phoenix – J.K. Rowling