A crossword clue in the Times 2 Jumbo Crossword Book—an assemblage of crosswords published in the Times—reads "use obscene language". The answer given is "eff and blind", confirmed by the entry in the Collins English Dictionary which is used as the authority for the crossword.
I'm a native (Australian) English speaker but the answer doesn't make any sense to me. An Australian driver might shout "Are you effing blind?" when another driver cuts across their path, but how is "eff and blind" actually used? The dictionary entry implies that the phrase is somehow the infinitive form of a verb ... but how is it used?