Drop A Brick Meaning

(US, idiomatic) Alternative form of drop a bombshell

Example: Used other than as an idiom: see drop,‎ brick.
1978, Ambroise Vollard, Violet M. MacDonald (translator), Recollections of a Picture Dealer, 2003, Dover Publications, 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?”
  â€œYou bet I do! I've not been able to get used to it these thirty years.”
  And as I stared at him, horror-struck:
  â€œYes. I'm her husband.”
1998, Harry Brewster, A Cosmopolite's Journey: Episodes from a Life, 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.
  â€˜I'm not a Christian, Harry.’