How to block someone who's already blocked you?

[Sankhyo]

Recently, I had a bad falling out with one of my friends on fb, and he blocked me. I know that once hes blocked someone, he has a tendency to unblock and revisit them just to sneak a peek.
So I myself tried to block him, but cant find his name when I search for it in the blocking section. Any ideas as how to ensure that he cannot view my account surreptitiously? 10 pts!

[Kai]

Well you can't do that cause he has already blocked you.

[Going with Logic!]

Its a tag game really - if you are already blocked - you are blocked .. but you can try and bypass this by putting in either his phone number or e mail address in the block settings ... or just wait and catch him when he unblocks