how about that

how about that

That is very interesting, impressive, exciting, surprising, or respectable. Said as an exclamation, rather than a question. A: "I heard Janet is running for a seat in the senate." B: "Wow, how about that!" How about that. Have you ever seen such a thing?
See also: how, that
Farlex Dictionary of Idioms.

How about that!

Isn't that surprising! A: My husband and I just celebrated our sixtieth anniversary. B: How about that!
See also: how
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

how about that?

Isn't that surprising, remarkable, or pleasing. For example, They're engaged-how about that? [Colloquial; first half of 1900s]
See also: how
The American Heritage® Dictionary of Idioms by Christine Ammer.

how/what about ˈthat (, then)!

(informal) used for expressing surprise, praise, great respect, etc: ‘Have you heard Jane’s been offered a film part in Hollywood?’ ‘Well, how about that, then!’
See also: how, what
Farlex Partner Idioms Dictionary

how about that

Informal
Used rhetorically to express surprise or wonder at or approval for something.
See also: how, that
American Heritage® Dictionary of the English Language, Fifth Edition.
See also:
  • hoo-rah
  • atcha
  • back at you
  • back atcha
  • ah
  • be still my beating heart
  • be still my heart
  • manual