That, under the circumstances, is a most unsuitable suggestion.
5 seconds sound clip from the Beat the Devil (1953) movie soundboard.
You can hear this line at 01:05:26 in the Blu-ray version of the movie.
Quote context
[...]
- How about you, dear Mrs. Dannreuther?
- I have the most fearful headache. I think I'll go to my cabin.
- Oh, what a shame. Well, boys, we'll have to make it cutthroat.
- What about Harry here? Maybe he'll take a hand.
- That, under the circumstances, is a most unsuitable suggestion.
- I must ask you to either move to another table or else leave the saloon.
- Oh, Harry, for heaven's sake.
- I don't care for my wife to associate with an associate of criminals.
- Don't be absurd. Billy's not a criminal.
[...]