Who would have thought?

who would have thought

It is very surprising (that something happened or is the case); no one could have predicted (that something happened or is the case). Who'd have thought that Ted would turn out to be a supermodel? I mean, just look at this old yearbook photo of him! Wow, I can't believe I actually got the promotion, and over Sarah, no less. Who would have thought?
See also: have, thought, who
Farlex Dictionary of Idioms.

Who would have thought?

 and Who could have thought?
a question phrase indicating surprise or amazement; I would never have guessed that something so surprising could happen. (No answer is expected.) Tom: Fred just quit his job and went to Africa. Bill: Who would have thought he could do such a thing? Andy: They say Bill is training for the Olympics in his spare time. Rachel: Who would have thought?
See also: have, who
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • who would have thought
  • who could have thought
  • frown
  • frown at
  • frown at (someone or something)
  • give (someone) a red face
  • give a red face
  • sea dog
  • old salt
  • win out over (someone or something)