This is what you want: ||facebook.com^$domain=~facebook.com|~facebook.net|~fbcdn.com|~fbcdn.net ||facebook.net^$domain=~facebook.com|~facebook.net|~fbcdn.com|

This is what you want: ||facebook.com^$domain=~facebook.com|~facebook.net|~fbcdn.com|~fbcdn.net ||facebook.net^$domain=~facebook.com|~facebook.net|~fbcdn.com|~fbcdn.net ||fbcdn.com^$domain=~facebook.com|~facebook.net|~fbcdn.com|~fbcdn.net ||fbcdn.net^$domain=~facebook.com|~facebook.net|~fbcdn.com|~fbcdn.net The key is to allow FB's CDN when on FB, but to disallow it and everything else when not on FB. I'm never on FB so this takes care of it nicely.