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Answer: both of them ditched their official names for their acronyms.

AAAA

Ad Age, April 2009:

President-CEO Nancy Hill told attendees that the group, for years known as the American Association of Advertising Agencies, has officially traded its name for its more commonly used acronym, the 4A's.

AARP

The New York Times, August 1999:

The American Association of Retired Persons is no longer the American Association of Retired Persons. It is AARP, and Horace B. Deets, its executive director, insists that, &39;&39;It is no longer an acronym.&39;&39;

What’s next? The American Automobile Association? The American Anthropological Association? Share your predictions in the comments.