I (do) declare! old-fashioned expression informal
Used to express surprise.
A: Congratulations! You have passed the exam. B: Well, I declare!
Peter: Did you know that she gained promotion? Linda: I declare!
To be surprised by some sudden occurrence
To greatly surprise, shock, or confuse someone
Used when something unpleasant has happened that has spoilt what you intended to do
Oh, no, that’s torn it! I’ve left my wallet at home!