Also,
rub it in. Harp on something, especially an unpleasant matter, as in
She always rubs in the fact that she graduated with honors and I didn't, or
I know I forgot your birthday, but don't keep rubbing it in. This idiom alludes to the expression
rub salt into a wound, an action that makes the wound more painful; it dates from medieval times and remains current. [Mid-1800s] Also see
rub someone's nose in it.