A Net-Twit is an over user of the popular site "twitter". Net-Twits feel important by replying to celebrities and posting their own tweets and pretending that people follow. The other guideline to being a Nit-Twit is that they log into twitter multiple times per day and are addicted to it.
"Jenny just tweeted that she had a massive dump. That is her third tweet already today! What a Net-Twit."