Redirecting Firefox when keywords are detected in URL

This is just on the local computer - *my *Firefox installation. When someone types a URL, if it has a certain word in it, I want Firefox to redirect to a certain page.

So basically, someone opens Firefox on my PC and types http://www.hax0rspywareandwarez.com, and “warez” is the magic keyword, they get redirected to another page.

Does such a thing exist?