This play on words is a pretty okay joke.
I'm cringing currently. It seems funny now, but in ten years, it'll be as funny as a Java class file's header being 0xCAFEBABE is.
0xCAFEBABE isn't laugh-out-loud funny (not sure it ever was), but I find it a comforting reminder that Java was actually written by humans. The "Duke" mascot, too. It's not at all hard to imagine an underemployed middle manager learning about it and demanding it being changed, in fear that the Important and Serious people who would write Important and Serious software in Java would think it's not an Important and Serious language.