How to block someone on Twitter without them knowing?
How can I block a friend that constantly Tweets and re-Tweets things in which I have no interest? I don’t want to hurt her feelings, so I don’t want to her to know that I’m blocking her. Is this even possible?
"To block a Twitter user: Log in to your Twitter account. Go to the profile page of the person you wish to block. Click the gear icon on their profile page. This brings up a drop-down actions menu. Select Block from the options listed.
Blocked users cannot: Add your Twitter account to their lists. Have their @replies or mentions show in your mentions tab (although these Tweets may still appear in search). Follow you. See your profile picture on their profile page or in their timeline."
If you use a mobile app like Tweetdeck or HootSweet, you can mute individuals without it being obvious. They both have a mute feature that basically makes tweets invisible from people that you don’t want to hear from.