until you are blue in the face
until (one) is blue in the face
For a great or unending length of time; until one has done it to exhaustion. You can complain about it until you're blue in the face, but you're going to school today whether you like it or not. They are such strange friends. They'll argue until they're blue in the face, then they'll go out for dinner and be the best of pals.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
until you are blue in the faceINFORMAL
If you say that someone can say or do something until they are blue in the face, you mean that however many times they say or do it, it will have no effect. You can speculate till you're blue in the face, but you can't prove a thing. The president can issue orders until he is blue in the face, but no-one will take any notice.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012