a different ERR_ACCESS_DENIED

I was able to define deny access web access at a certain times of the day some
web sites, specifically porn sites.

My ERR_ACCESS_DENIED message is:

ERROR

The requested URL could not be retrieved

While trying to retrieve the URL: http://yahoo.com/

The following error was encountered:

     Access Denied.

     Access control configuration prevents your request from being allowed at
this time.
     Internet access is available only on the following hours:

                       from to

         Sunday 0000 hrs 0300 hrs
                      1700 2359
         Monday 0000 2100
         Tuesday 0600 2100
         Wednesday 0600 2100
         Friday 0600 2359
         Saturday 0000 2359

However, I want to have a different ERR_ACCESS_DENIED message for porn sites
that I wish to disallow. How do I configure a different error message squid
such that it looks for example into my listed (denied) access control list
(playboy.com or sex.com) and returns an error message stating those porn sites
are not allowed?

Sample error I wish to have for disallowing those porn sites is:

ERROR

The requested URL could not be retrieved

While trying to retrieve the URL: http://sex.com/

The following error was encountered:

     Access Denied.

     Access control configuration prevents your request from accessing porn
sites.

Awaiting someone's reply,

Joel