Ennis humorously told Jack, "You'll run them damn sheep off again if you don't hush up." In fact, being able to sing and play music was so important to keeping the animals calm, that sheepherders who didn't sing or play music often wouldn't be hired. What Ennis really meant was, "You'll run me off if you keep makin love to me like that." Jack wisely paid him no heed.
=reply= Toast
I still have not found a reference to Yosemite in the movie, but since I replaced it with another "Y" word as soon as Fran XXX'd the Yosemite, there is no rush. BTW, my name is Front-Ranger.