till you're blue in the face
till (one) is blue in the face
Of something vocalized, for a great or indefinite length of time. You can complain about it till you're blue in the face, but we're going to your grandmother's for Thanksgiving whether you like it or not. They are such strange friends. They'll argue till they're blue in the face, then they'll go out for drinks and be the best of pals.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
(do something) till you’re ˌblue in the ˈface(informal) (do something) with a lot of effort and for a very long time without success: You can argue with John till you’re blue in the face, he’ll never agree with you.
Farlex Partner Idioms Dictionary © Farlex 2017