Or take a more direct route and simply have it serve up a page that says "HEY PARASITE: GET YOUR OWN #%#$& INTERNET ACCESS!"
At least that way they'd be immediately aware he knows they're leeching off of him. Depending on who's doing it, they're liable to be so stupid they don't realize he's screwing with them and they're bugging Dell tech support and asking them why their "internet is upside down". -- I'd kill for a Nobel peace prize!
