"I mean, they grow some of that stuff in dirt you know," he tells Xellos in withering tones.
Rincewind sighs, gets to his feet, kicks at the plate, then picks it up. "Mutter, mutter, mutter," he mutters, setting the plate on his head hard enough to crack it. "OOPS!" He gives Xellos a sidewise glance, hoping he didn't notice.
I'm truly sorry about that mental image. That's bound to echo on the ethereal plane, or wherever it is that Xel goes sometimes.