until the cows come home
(idiomatic) For a very long period of time.
You can crank the engine until the cows come home, but it won’t start without fuel.
I can drink tea until the cows come home and I love the atmosphere in tea-shops. Zola Budd
In the theatre, people talk. Talk, talk until the cows come home about journeys of discovery and about what Hazlitt thought of a line of Shakespeare. I can't stand it. Anthony Hopkins
You can do gross-out until the cows come home but if there isn't something to balance it, then it's not going to work at all. Curtis Armstrong