Broccoli vs Little Girls

Listen here, you little twit, let me break this down for your smooth brain. You know how you thought the joke would be some kind of normal comparison? But it turns out the punchline is that they don't like the taste of broccoli? It's a dark joke because it implies something horrible about what the speaker would do to little girls. It's not even subtle like you usually like it, it goes straight for the punchline.