But the author had to devise a trick parents can use at home when their kids decide to whip out the "Avada Kedavra" curse (that "kills people" in the film).
It all started when a mother tweeted Rowling about her 'Harry Potter' related issue.
"@jk_rowling My son's using 'Avada Kedavra' on me instead of saying 'I hate you'," Twitter user TriedUntrue wrote.
And it seemed the mum wasn't the only one who was enduring the curse from her child.
Luckily for parents, Rowling stepped in with the perfect response to any child who uses the curse at home.
"Tell him your love would protect him from that curse," she wrote.
"Do Dobby eyes as you say it. Should scar(e) him out of it."
Rowling's fans loved her witty and imaginative response.