We're not sure exactly what this person said to get this pop star so upset.
But whatever it was it provoked an AH-Mazing response!
Selena Gomez recently shared a screenshot of a comment she left on one person's wall, and it seems like that person had wished cancer upon someone.
Which Selena took great offense to, and decided to fight the bully with her intelligence. Which is always the best way to deal with bullies. Selena then shared what she said on her own Instagram. Here's what she said to the bully: