would turn in your grave
turn (over) in (one's) grave
To (hypothetically) show enormous anger, disfavor, or regret for someone's actions or something that happens after one has died. That is, if someone were still alive, they would be greatly upset, angered, or disgusted by what has happened. I can't believe you're using our employees' pension payments to prop up a Ponzi scheme. The founder of this once-great company would be turning in his grave to see its directors stoop so low. Your poor mother would turn over in her grave if she heard the horrible things you were saying about your sister. I can't believe you wrecked your grandfather's prized truck. That's enough to make him turn over in his grave!
would turn in your graveBRITISH or
would turn over in your graveAMERICAN
COMMON If you say that someone who is dead would turn in their grave, you mean that they would be very angry or upset about something which is happening now, if they knew about it. Churchill would turn in his grave if he could hear the poor quality of the public speaking in Parliament these days. If the person who wrote that song could hear that guy sing it, he'd turn over in his grave. Note: You can also say that someone would be spinning in their grave. My grandfather would be spinning in his grave if he could see what had been done to his house.