tweetcreep
To follow someone on twitter but not engage in the conversation or let it be known that you are watching the twitter conversation. - Or to only post the words tweetcreep to let everyone know you are "creepin" on their tweets.
"I tweeted that we were all going to meet up at John's tonight. Derek showed up there uninvited.. Said he saw it on my twitter. What a tweetcreep!!