Because she's black. Get it?
What you have before you is the face of a man who decided that one cool way to congratulate a beloved black author on her career-marking literary award—Jacqueline Woodson, who wrote YA award-winners Miracle Boys and Show Way, and whose work explicitly addresses black identity in America—would be to make a joke about how she's allergic to watermelon.
After Woodson's heartfelt acceptance speech for her National Book Award, the ceremony's host—Daniel Handler, also known as Lemony Snicket—says this:
I told you—I told Jackie she was gonna win, and I, uh, said that if she won, I would tell all of you something I learned about her this summer. Which is that Jackie Woodson is allergic to watermelon. Just let that sink in your mind. And I said, you have to put that in a book. She said, YOU put it in a book. And I said, I'm only writing a book about a black girl that's allergic to watermelon if I get a blurb from you, Cornell West, Toni Morrison and Barack Obama saying "This guy's okay, this guy's fine." [Laughs] Alright, we'll talk about it later.
Previous to this, Handler introduces Sharon Draper, another award-winning black author, by mentioning that she's won the Coretta Scott King Award—"a prize I hope to one day receive myself. That's a children's publishing joke. We'll explain it to you later."
The Coretta Scott King Award is awarded to African-American youth-market writers and illustrators whose work is centered on African-American experience. For further context, about 3% of children's books published in America are written by black authors or prominently feature black characters.
Handler's Lemony Snicket series has sold over 60 million copies, been adapted into a big-budget movie, and been translated into more than 40 languages. The main characters in the Lemony Snicket series are white. And he's still talking.
However, though it was certainly Daniel Handler who showed his ass here, the "joke" is really not on him but on the writers in any sort of minority group, who will be reminded that they are amusingly, fundamentally Other, even at a moment that marks a highlight of an already incredible career.
Video of the whole ceremony is up here. Handler also apparently referred to two black poetry nominees as "probable cause."