For Unix Geeks only:

gateway# crontab -l
0 12 * * 1-5 /sbin/ipfw add 666 deny tcp from any to any 3724
0 20 * * 1-5 /sbin/ipfw delete 666


If you don't understand, I am so glad for you. Seriously.

If you absolutely must know, here's a spoiler (select the white text to the right of this phrase): World of Warcraft uses the TCP protocol on port 3724.