space walnut

some sort of insult in Steven Universe, introduced in the episode "Gem Harvest".

Only used once after Greg confessed to his cousin Andy that he changed his family name from Demayo to Universe.

Steven: "what's a Demayo?"
Andy: "Andy Demayo, Greg Demayo, Steven Demayo. We're the Demayos."
Greg: "actually, we're, uhm, the Universes now."
Andy: "YOU SPACE WALNUT! you didn't even kept your family name! But you go around giving family property out like candy on some kind of candy giving out holiday?!"