Ignore an individual Signature or Avatar

[Insert Username]

Here's what I'd like to do: I'd like to be able to set one user's avatar or signature (sig in this case) to be turned off for another user. Say this person has a signature that someone else finds offensive. I don't want the offended person to have to turn off sigs board-wide...I'd just like to turn off the one sig for that one user. Being able to do it for avatars would be nice, too.

Any thoughts?