a nod is as good as a wink to a blind horse
It is unnecessary to explain or elaborate upon something because one already understands or knows about it in full. No need to tell me what you were up to last night—a nod's as good as a wink to a blind horse.
nod is as good as a wink to a blind horse
Prov. You cannot get people to take a hint if they are determined not to. Jill: I keep hinting to the boss that I deserve a raise, but he doesn't seem to get the point. Jane: I'm not surprised. A nod's as good as a wink to a blind horse.