(Assuming bind is the DNS server on the router, and that your computer is using said router for DNS resolution. Edit: If your computer is using your ISPs DNS servers directly, this won't work at all. Skip to the iptables section.)
Bind isn't going to use the local server's /etc/hosts to find out what facebook is. If you want to break facebook you'd need to tell bind that it's authoritative for the facebook.com domain, and set up a zonefile with 127.0.0.1 (for example) as the A record for facebook.com and www.facebook.com.
A simpler approach might be to add iptables rules for the IPs used by facebook.
iptables -I FORWARD -s <computer IP> -d 184.108.40.206 -p tcp -j REJECT
iptables -I FORWARD -s <computer IP> -d 220.127.116.11 -p tcp -j REJECT
iptables -I FORWARD -s <computer IP> -d 18.104.22.168 -p tcp -j REJECT
That or self-control :-P.