How is “the damnedest” used?

In Barfly (1987), one line is: “Yeah, you're the damnedest barfly I've ever seen.”

Which movie is “the damnedest” from?

The clip at the top of this page is from Barfly (1987).

the most surprising…; The most extreme or thorough example of a person or kind, used to praise or to blame

American · Heard in 4 movies

Oxford75% of films
the most surprising…
Isn't that the damnedest thing?
It's the damnedest thing.
Editorial25% of films
The most extreme or thorough example of a person or kind, used to praise or to blame

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

Yeah, you're the damnedest barfly I've ever seen.

Said in 8 films · #1