For the record I mostly (if not completely) agree with @kseniaanske's Ello post here on methods for selling your books like hotcakes (or selling any of your work or services in general). That said though, the theme of "selling" reminds me of a recent Facebook post from Existential Comics, as above.
I personally find the above joke hilarious. But regardless I do realize that humor is highly subjective.
Link to FB: [+]
Also Existential Comics are much, much funnier at their own website: www.existentialcomics.com.