Why are people using "coconut" in references to Kamala Harris?

"My mother ... would give us a hard time sometimes, and she would say to us, 'I don’t know what’s wrong with you young people. You think you just fell out of a coconut tree?' " Harris said with a laugh. "You exist in the context of all in which you live and what came before you."

That's actually kinda nice. I can appreciate that. We're all the middle children of history, in a way.