According to the mouse-over text in http://xkcd.com/903/, “if you take any article (in Wikipedia), click on the first link in the article text not in parentheses or italics, and repeat, you will eventually end up in ‘Philosophy‘.” I just tried it. Here’s the sequence, which the phrases that create the first link, almost producing a series of Backus–Naur Form expressions.
I started with the old pen-and-paper role-playing game Gamma World, which I was looking up while writing about games, rules and authorship:
- Gamma World is a science fantasy role-playing game . . .
- Science fantasy is a mixed genre within speculative fiction . . .
- A cross-genre (or hybrid genre) is a genre in fiction . . . 
- A literary genre is a category of literary composition. Genres may be determined by literary technique . . . 
- A literary technique, literary method, literary devices, or literary motif is an identifiable rule of thumb . . .
- A rule of thumb is a principle . . .
- A principle is a law or rule . . .
- Law is a system . . .
- System . . . is a set of elements . . . 
- In mathematics, an element or member of a set . . .
- Mathematics is the study of quantity . . .
- Quantity is a kind of property . . .
- In modern philosophy, mathematics and logic, a property is an attribute of an object . . .
- Modern philosophy is a type of philosophy . . .
- Mixed genre redirects to cross genre.
- Genre redirects to literary genre.
- If you violate the rule to ignore links in parentheses or italics, you wind up going to Latin, then Italic Language, Indo-European languages, Language family, language, human, taxonomy, science . . . and eventually back to philosophy. It is possible to hit a loop at some point, depending on where you decide to adhere to the “no parentheses/italics” rule.