When you are super happy and girly. You are often complementing someone who did something mean to someone else that was funny. You also want to act cool, and like you don't care about anything but you really do. Often a youtuber.
Person 1: hey girl!!!!! i totally dissed that guy back there!
Person 2: YASSSSS QUEEN!!!!!!!!
This word/words can be used in a sentence in many occasions. It is used by girls that are amazing and love their friends or the people that they are using it toward.
GIRL, "Guess what!!! I won my cheer contest!!!!!!" OTHER GIRL, "OMG YASSSSS SLAYY QUEEN!!"