If you look at the picture below which rita posted on Instagram of her, Ellie, Katy, and Calvin at the EMA's and you look at the caption, you'll understand the shade. In case you dont, let me break it down for you.
In the picture, Ellie is all the way to the left, so look at the first emoji she posted, it's for Ellie.
if you look at the second one, it's the classic "I'm a bad bitch" emoji for katy becase she likes katy. if you look at calvin and then the third emoji she used, it's of a guy thinking, and if you look at the last emoji, and you can see she's all the way on the right, she used the "hand raise/me" emoji
http://www4.picturepush.com/photo/a/...mous/image.jpg
I bet she thought no one would catch it
QUEEN
a girl crossing her arms, a waitress pose, a guy sulking, and a girl raising her hand 
