before you can say (something)

before you can say (something)

Very quickly or suddenly. (The idea being that something will happen so fast that you won't have time to articulate it.) I'm not far from your house, so I'll be there before you can say "when." Default on your mortgage repayments again, and the bank repossess everything you own before you can say, "We're broke!"
See also: before, can, say
Farlex Dictionary of Idioms.
See also:
  • take on (a) new significance
  • burst out of (somewhere or something)
  • take on (a) new meaning
  • a light bulb goes on in (one's) brain
  • a light bulb goes on in (one's) head
  • burst (up)on the scene
  • burst on the scene
  • burst onto the scene
  • cock up
  • default on