Exactly. These links are not meant to be posted online or meant to last forever. The main use-case is to share them aloud with other people in the room (or write them on a whiteboard at a hackathon). I mention quite clearly that the links are temporary, so people that use them otherwise are missing the point I think.

So ideally you want people entering links directly into the url bar instead of creating a page link somewhere. You could detect that reasonably well with the Referer header, and perhaps provide a warning against that behavior? food for thought

It might be terrible from a usability stand point (or it might be an improvement), but if the point is to share the link verbally and not via a text link [or if doing so will litter the web with broken links], why support direct links at all?

Why not just have an input box on the home page? The user puts in the english word, and you do the redirect.

then rather than just type one url in and get redirected, they have to remember to type in a url, then type in a word. its easier as it is.

I understood that, but rarely do people use services exactly as they are intended unless somehow forced to.