Someone on your post being a troll, spamming, or just being a freaking jerk? You could just click a button to "hide" their reply so that you won't have to put up with that reply, or just make all their replies invisible so you'll never have to put up with their stupidity again. This would apply to all people on a post written by you, but only to you on other posts. You would also be able to hide any and all posts by this person: Totally optional and once again only applying to you.
Whaddya think, Senn? (^v^)