How is “a snake” used?

In His Girl Friday (1940), one line is: “He comes by it naturally. His grandfather was a snake.”

Which movie is “a snake” from?

The clip at the top of this page is from His Girl Friday (1940).

a person who pretends to be your friend but who cannot be trusted; a long, legless reptile

disapproving · Heard in 28 movies

Oxford40% of films
a person who pretends to be your friend but who cannot be trusted
Editorial7% of films
a long, legless reptile

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

He comes by it naturally. His grandfather was a snake.

Said in 8 films · #1