Someone who excessively uses the popular social networking site, "Twitter". Also, someone who talks excessively of twittering tweets on Twitter, or uses other obnoxiouswords like Tweeple, Tweetup or Twictionary.
My Twitterati friends and I have been on Twitter way longer than you, Twerp.
1. n. A surprisingly, but not impressively unclean vagina. May be the effect of one or more sexually transmitted diseases or failure to clean and/or maintain during menstruation.