that's not your pidgeon

phrase used to point out to someone that they are out of their jurisdiction or speaking out of place. Used in instances when someone is making comments or decisions that are not related to their expertise, knowledge base, or responsibility.

Burns: "I wish Marge were here to give me a back massage."

Smithers: "Mr. Burns, I would be happy to give you a back massage."

Burns: "Smithers, that's not your pidgeon."