What a backronym is (also commonly spelled bacronym).
In short, a backronym is when you treat a word that is not an acronym as if it was an acronym, constructing a phrase out of the word. For example: Delta – Doesn’t Ever Leave The Airport
Backronyms are often used for humorous effect as in the example above, but they are also quite commonly used unintentionally. For instance, many people believe the word “wiki” is an acronym for “What I Know Is”, but in fact it is not. The word ‘wiki’ is derived from the Hawaiian phrase “wiki wiki”, meaning ‘fast’. Thus used as: wiki – What I Know Is, makes this an example of a backronym.
The earliest known reference to the word backronym in print was in a November 1983 edition of the Washington Post monthly neologism contest. more
Here are some that I’ve heard:
FORD = Fix Or Repair Daily
IROC= Italian Retards Out Cruising
KIA = Korean Industrial Accident
SWAG= Stolen Without A Gun
BING= Bing Is Not Google
FIAT= Fix It Again, Tony