They don't call her "J.K." because she's so serious on Twitter.

@jk_rowling, center. (via Getty)

Today is J.K. Rowling's birthday. Another year goes by. Accio the march of time. In the Harry Potter author's honor, let's look back at her most delightful trolling moments and refrain from practicing any dark arts for the rest of the day.

1. The time she played an elaborate mind game to make us think we all went to Hogwarts.

2. The time she expressed second thoughts about typing all your favorite characters to death.