If it's whistling a tune or singing a song, they all say howdy when you come along.
6 seconds sound clip from the Song of the South (1946) movie soundboard.
You can hear this line at 00:44:45.794 in the Blu-ray version of the movie.
Quote context
[...]
- Sticking my foot in it, Uncle Remus?
- Ain't you never heard that tale?
- Lordy me, I declare to gracious. I sure ought to told you about that.
- Well, sir, once upon a time... not your time, nor yet my time, but one time, I was going fishing.
- If it's whistling a tune or singing a song, they all say howdy when you come along.
- Good morning, good morning, girls.
- Oh, good morning, Miss Nellie.
- What goes up is sure to come down.
[...]