I have two sons. This one and this one. Now one day this one didn't have to go to
school and this one did. Well this one didn't really want to go to school so
this one said, "Oh, you have to go to school? Too bad, I don't have to go to school today.
And we said, "Stoney, don't rub it in! Don't rub it in his face."
To rub something, it means to emphasize it usually when it's something negative
like Sawyer didn't want to go to school so Stoney was rubbing it in
that he didn't have to go to school. And to rub it in his face just means the same thing.
Don't rub it in, don't rub it in his face. They are cute though, aren't they?