Originally posted by Serenity
FLAK
"Flugabwehrkanone"
Anti-Aircraft Defense Cannon
Hmmm...while yes, Ack-Ack does refer to anti-aircraft artillery it doesn't come from any German references. It is widely believed that Ack-Ack derived its name from the German "acht-acht" (88mm) but it's not the case. Ack-Ack originated in World War I, before the Germans had the 88mm, so you can cross that out as the origin of the word.
Ack-Ack actually has its origins from the RAF phonetic alphabet used in World War I.
Ack = A
So AA (Anti-Aircraft Artillery) was Ack-Ack using the RAF phonetic alphabet. Ack-Ack was also given the nickname "Archie" by the British Royal Flying Corp in World War I but was a nickname only and not derived from a phonetic alphabet.
Another example is AM, which in the RAF phonetic alphabet would have been Ack Emma and PM would have been Pip Emma
Emma = M
Pip = P
The RAF phonetic alphabet was eventually replaced by the NATO phonetic alphabet.
ack-ack