Well, Douglas, I guess it's because he earned it.
4 seconds sound clip from the McLintock! (1963) movie soundboard.
You can hear this line at 00:12:04 in the Blu-ray version of the movie.
Quote context
[...]
- And even the government should know that you can't farm 6000 feet above sea level.
- Douglas? Just plain Douglas, eh? And you call him Mr. McLintock. Why?
- Well, Douglas, I guess it's because he earned it.
- Yeah?
- I'm a good hand with cattle. I'd like a job.
- Well, you look strong enough.
- You come in with those sooners?
[...]