The phrase 'my momma said,' will take you back to a number of arguments you probably had with friends as a child. 'My momma said I'm not allowed to play at your house, because it's dirty.' 'My momma said your daddy didn't go to work abroad he left your momma.' It's the know-it-all kid who's heard something they shouldn't have done from their own parents about either you or your own parents, and is now reciting it back to you. Perhaps you even did this to other people!
As you might be able to tell if you know the story, or if you look closely at the picture, the little girl in the picture is actually megastar Cardi B. She sort-of did this to herself; she posted the picture to Instagram, and the memes started appearing the very next day.