Rubbing it in

What does it mean when an American says "Stop rubbing it in" and also, "I didn't get to sleep in." The two are not related. Thanks for you help.

"Stop rubbing it in" means "you've reminded me once that I was incorrect, and now you've repeated it, and repeated it, for the satisfaction it gives you to see my discomfort. Enough. You've made you point, so stop."

"I didn't get to sleep in" means something like "I wanted to sleep for 8 hours even though I went to bed at 2 in the morning ... but duty called and I had to get up for work at 7."

Could "rubbing it in" relate to the phrase "rubbing salt in someone's wounds," making a bad situation worse?

I never heard "sleeping in" for sleeping late until I moved from the rural area of West Virginia to the "big city." Maybe that's because country people never get to "sleep in."