I'll thank you to do something
I'll thank you to (do something)
Used to instruct someone to do something in a polite but firm manner, especially when one is angered or annoyed by someone's words or actions. Often used in the negative. I'll thank you to sit quietly during the proceedings, Mr. Turner, unless directed otherwise by the court. Unless you have a warrant, I'll thank you not to go through my personal items!
See also: thank