How do I block someone in a shared group on Facebook?

[Richard]

I'm in a group called The Nerd Herd on Facebook & I'm friends with just about all of the active members of the group (ones who are on a lot). There is this one guy who bugs the crap out of me though & I really would like to prevent him from commenting on my posts. It isn't anything mean, just annoying; on EVERY one of my posts he'll comment "what" & every time I comment after that he repeats "what" after I speak. He also does this after every single one of my comments on other people's posts. It's like he watches every post in the group for me just so he can get on my nerves & it's begun to piss me off. Can I block him? Or is there a way to prevent him from at least commenting on posts I put up in the group?

[avon]

Jus click on his profile and there should be a block option, click and confirm and he won't be able to see your future posts, you won't be able see his posts either