In terms of the xkcd quote ("'This space intentionally left blank' is less immediately provocative but more Hofstadterially confusing."), this means self-referencing. So the quote says "This space intentionally left blank", but by writing those words the space becomes not blank.
Hofstadter's law is a self-referencing law: "It always takes longer than you expect, even when you take into account Hofstadter's Law."