(Well,) I'll be blowed!

old-fashioned An expression of surprise or astonishment, especially regarding some recent revelation. 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 blowed, I didn't know that!" Well, I'll be blowed! Who knew so many people would show up to see our concert?

I'll be blowed

used to express surprise, annoyance, etc. informal