What's the greatest put-down in science fiction history?

Science fiction and fantasy require a lot of imagination and cleverness — so it's not surprising there are some epic insults in the genre. But what's the most cunning insult in all of science fiction and fantasy?

Please include a picture, clip or book cover for your chosen insult. And please mention the name of the work, and the actual text of the insult. Thanks!

Top image: "Nerf-herder" from Star Wars: Empire Strikes Back.