TALK THROUGH YOUR HAT to talk nonsense.
Everybody could see that he was talking through his hat. They ignored him.
You are talking through your hat. You know nothing about this.
TALK SHOP means to talk about business.
It’s the weekend. Please don’t talk shop all evening.
If you two are going to talk shop, I am going to leave.
TALKING UNTIL YOU ARE BLUE IN THE FACE means to talk on endlessly.
I talked until I was blue in the face but I couldn’t get her to change her mind.
You can talk until you are blue in the face but you will never convince me.