(Well,) I'll be durned!

(Well,) I'll be durned!

old-fashioned An expression of surprise or astonishment, especially regarding some recent revelation. ("Durn" is a variant of "darn.") Primarily heard in US. A: "You know, if you run your washing machine at night you can save a lot of money on your electric bill." B: "I'll be durned, I didn't know that!" Well, I'll be durned! Who knew so many people would show up to see our concert?
Farlex Dictionary of Idioms.
See also:
  • (Well,) I'll be blowed!
  • I'll be blowed
  • blowed
  • darned
  • I'll be darned!
  • (Well,) I'll be darned!
  • (well,) I'll be hanged!
  • (well,) I'll be!
  • I'll be hanged
  • I'll be!