have a gun to (one's) head
To force or pressure one (to do something). Kristina, you don't have to move if you don't want to—no one has a gun to your head.
have a ˈgun to your head
(informal) be forced to do something that you do not want to do: ‘Why did he go back to his wife?’ ‘Because he had a gun to his head. She said she would never let him see the children again.’