Green’s Dictionary of Slang

(orig. US milit.) to mess up, to go wrong, esp. in a complex, elaborate manner.

1947		(con. 1944) J.H. Burns Gallery (1948) 292: I snafu’d just like the rest of them.
1951		R. Leveridge Walk on the Water 263: Maybe the Army Post Office snafued again!
1954		B. Appel Sweet Money Girl 142: Things all snafued between the boy and the girl.
1956		Mad mag. Nov.–Dec. 38: The crowd roared as Fenwick snafued the onion.
1972		N. Conway Bloods 20: ‘We’ll never make soldiers of them,’ was Milligan’s comment after a morning of ‘As you WERE’ commands, every time one of the newcomers snaffood a simple right or left turn.
1994		D.E. Axinn Spin 149: She’s reminding me I snafued it.