till you're blue in the face

You can tell people till you’re blue in the face that, if they want to save money, they have to earn more than they spend.

From Washington Post ● Oct. 15, 2021

You can tell diners, till you’re blue in the face, about the benefits of kelp aquaculture, but unless the seaweed bowl tastes good, few will care enough to keep buying it.

From Washington Post ● Feb. 11, 2020

I’ll do this till you’re blue in the face.

From Washington Post ● Jan. 14, 2016

“None of this means anything anymore. You can scream till you’re blue in the face, and still be standing in the same place,” I said.

From "The Rock and the River" by Kekla Magoon

Mrs Gowler rose unsteadily to her feet and said: "Ten quid down will save you from forking out five bob a week till you're blue in the face from paying it."

From Sparrows: the story of an unprotected girl by Horace W. C. (Horace Wykeham Can) Newte