(well,) I'll be!
An expression of surprise or astonishment, especially regarding some recent revelation. Bob: "You know, if you run your washing machine at night, you can save a lot of money on your electric bill." John: "I'll be, I never knew that before!" Well, I'll be! Who knew so many people would show up to see our concert?
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
(Well,) I'll be!
Rur. I am very surprised! Charlie: Joe and Sally got married last weekend. Jane: Well, I'll be! I'll be! Bill got the top score on the test!
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.