used for questions which directly refer to or are inspired by XKCD or related material.
XKCD is a webcomic created by Randall Munroe which frequently makes reference to sci-fi and fantasy pop-culture material. The main comic is at xkcd.com and a longer format less frequent related site is what-if.xkcd.com. In addition, Munroe has written two similarly style books titled What If?: Serious Scientific Answers to Absurd Hypothetical Questions and Thing Explainer.