It started innocently enough, with a congrats from JK to Serena on her Serena Slam.

#SerenaSlam! I love her. What an athlete, what a role model, what a woman!

— J.K. Rowling (@jk_rowling) July 11, 2015

But then poor innocent Rob decided to troll his way into a world of twitter hurt:

@jk_rowling @hansmollman ironic then that main reason for her success is that she is built like a man

— Rob (@diegtristan8) July 11, 2015

Lesson: Don’t mess with a writer who has a way with words:

.@diegtristan8 “she is built like a man”. Yeah, my husband looks just like this in a dress. You’re an idiot. pic.twitter.com/BCvT10MYkI

— J.K. Rowling (@jk_rowling) July 11, 2015

As of the time of writing, it’s already been favorited more than 100,000 times.