Cock-up??
Oddly, in British English it is not these days a vulgarism, or at least only a very mild one. It comes from one of several senses of cock, to bend at an angle, as in — for example — cocking a gun or turning up the brim of one’s headgear (so producing an old-time naval officer’s cocked hat).
The use of cock-up to mean a blunder or error was originally British military slang dating from the 1920s. The slang sense of cock clearly had a lot to do with its adoption, but this hasn’t stopped it being used in respectable publications, and modern British dictionaries mark it merely as informal or colloquial.