Also Can Be Phrased:
Rolling over in her grave.
Turn over in one's grave.
Implies that something would anger the referenced person who is dead if he was still alive.
To say that someone would be rolling over in their grave implies that they would be so upset and uncomfortable by something that just happened that they would turn over in their grave. It is an exaggeration of the fact that when somebody is uncomfortable, it is common for them to shift their weight, or roll over if they are sleeping. This idiom implies that someone would be so upset by something that they would roll over, even though they are dead.
Your grandfather loved that house, I can't believe you tore it down. He must be rolling over in his grave.
You know your sister doesn't want us fighting. She's probably turning over in her grave right now.
If your mother heard you say that, she'd be turning over in her grave.