I like the suggestion to sign him up for spam lists. A good way to do this is by posting to Usenet with his email address. You can even do this 'honestly' by posting questions to various games or admin.* Groups asking for advice about his request and including the full email and headers (erm, with your OWN email removed to preserve your own privacy from the spammers..
Or if you're really evil you could post _AS_ him and do something nasty to get him in additional trouble. Address 'harvesters' will then pick up the address and add it to lots of spam lists at once. This is much more efficient than going out a manually filling in forms.