Green’s Dictionary of Slang

(orig. US milit.) to blunder, to make a mess, to make a mistake.

1946		‘J. Macdougal’ in Astounding Science Fiction Oct. 55/1: Well, there are a lot of minor ones, which must have fubared things in all directions once Co-ordination accepted them .
1953		(con. WWII) L. Uris Battle Cry (1964) 118: Fubar on the nets and you can louse up an entire landing team.
2004		(con. 1965–73) D. Flaherty Pipes Were Calling 70: Canton yelled in a frenzied voice, ‘I hope they took off or we’re FUBARed for sure!’.
2004		W.J. Wood Jr Mothertime 256: The bookends looked at each other. The jig was up. Unforseen circumstances. FUBARed.