the pits, (it's)

It can’t get any worse than this; wholly objectionable. Originating in America in the second half of the twentieth century, this expression is nonetheless mysterious in origin. Some speculate that it originally meant the coal pits, an unpleasant place for miners; some think it alludes to armpits, traditionally a smelly place. The American humorist Erma Bombeck played on it in the title of her book If Life Is Just a Bowl of Cherries, What Am I Doing in the Pits? (1978). And Robert Barnard (Death and the Chaste Apprentice, 1989) has a character say, “I think anyone would have been a letdown. But Capper she thought the absolute pits.”