From Homestar Runner Wiki
When a link is entered on a page that points to a page in the main, project, user, or help namespace, the system first tries to match it exactly as it's written. If the page does not exist, the system automatically tries to create a hidden piped link to a capitalized/lowercase or plural form (except it does not attempt to match plural forms for the user namespace). Similarly, if the system cannot find a page based on a URL, it tries to automatically create a redirect. What this means is that it is no longer necessary to create a piped link from goat to Goats, for example, and it is not necessary to have a corresponding redirect page. Pages where the capitalized and lowercase forms mean different things, like Homsar and homsar, are unaffected.
If it should ever become necessary to create a page that ordinarily would be autoredirected, just type it into the URL, and you'll be presented with a "redirected from" link, such as. Then create the page like normal.
Note that even though double (and triple) redirects are supported by the wiki, they are not currently incorporated into this feature. If an autoredirected title is part of the redirect chain, it will require a click-through.
Just for fun, autopi is also supported.