drop a brick

English

drop a brick (third-person singular simple present drops a brick, present participle dropping a brick, simple past and past participle dropped a brick)

(UK, idiomatic) To commit a faux pas, especially in speech, such as by tactlessly speaking of a subject that should not be mentioned.
- 1978, Ambroise Vollard, translated by Violet M. MacDonald, Recollections of a Picture Dealer, Dover Publications, published 2003, page 28:
  It was on one of those Tuesdays that I dropped a brick, the memory of which still haunts me after more than forty years. A very loquacious lady, whom I had never seen before, appeared to be talking through her nose. “Don't you think,” I said to one of my neighbours, by way of starting conversation, “that lady would be well advised to sound her trumpet less often?”
  “You bet I do! I've not been able to get used to it these thirty years.”
  And as I stared at him, horror-struck:
  “Yes. I'm her husband.”
- 1998, Harry Brewster, A Cosmopolite's Journey: Episodes from a Life‎^[1], page 216:
  I remember dropping a brick when I first met her. As she at once started calling me 'Harry' in the way Americans are apt to do, the surname becoming immediately superfluous. I ventured to ask her what her Christian name was.
  ‘I'm not a Christian, Harry.’
(US, idiomatic) Alternative form of drop a bombshell
Used other than figuratively or idiomatically: see drop,‎ brick.
The clumsy builder dropped a brick on his toe.