1) Rename the file(s). 2) Have your pages point or link to the new filenames. 3) Have lots of fun with the OLD file names, as in really original content You could point out the hot-linking or put up something raunchy. Use your imagination! -Larry
To avoid confusing legimate users who may have bookmarked your site, I'd simply do an htaccess level ban of the offending site and have your server serve something something subtley incorrect instead. Bad grammar, bad spelling, incomplete information. Make them look bad, but in a way they may not immediately realize. Serving a nudie is immediately obvious. Serving a page full of typos and bad info? Not so obvious. And now they have this "created by" tag on it claiming THEY wrote the bad article....
If you know what IP they're accessing the web with (likely not the same IP as their site) you can further stymie them by having your site serve a blank page whenever they try to access it, or redirect them somewhere obnoxious. (My site just says the site's down when I ban an IP.)
But DON'T move the file and replace it with something rude or crude. Because likely your legitimate users may have some of the files bookmarked. You don't want someone innocent getting an eyefull.