NSF: Not So Fast   

Know what AJR stands for? Guess again. Sadly, the first entry to appear on Google is the American Journal of Roentgenology, a peer-reviewed journal published by the United States' oldest radiology society. Some other surprising alternatives to otherwise obvious acronyms:

NSA (National Security Agency)
National Softball Association
National Scrabble Association
National Shellfisheries Association
National Stuttering Association

FDA (Food and Drug Administration)
Flying Dentists Association
Florida Dart Association

CIA (Central Intelligence Agency)
Culinary Institute of America
Cosmic Internet Academy

NBC (National Broadcasting Company)
National Baptist Convention
National Broiler Council (the former name of the National Chicken Council)
National Bridge Conference (for builders, not players)

PBS (Public Broadcasting Service)
Professional Bowhunters Society

WTO (World Trade Organization)
World Toilet Organization

USA (United States of America)
Unicycling Society of America

Sources: Google and other Web sites