Demi Lovato Videos: TwitterBreak: With a "Guess who's baccckkk...." tweet, Demi Lovato reentered the Twit-o-sphere -- whether she'll be her old tweetaholic self again remains unknown. Demi simply signed on to encourage her followers to bid on a tweet from her.

"I'

m in the online charity auction & would LOVE for you to bid! Starts TODAY!" she told her almost 2.5 million followers. TwitChange is the first celebrity tweet auction where fans and companies looking for a big shout-out can bid to be followed by their fave celeb, retweeted, or mentioned by them in a special tweet.

Bidding will end on September 25, and all proceeds will benefit aHomeInHaiti.org. The charity is currently rebuilding the Miriam Center, a home for Haitian children with cerebral palsy, severe autism, and other major life challenges.

Demi, who supposedly quit Twitter because of haters, is spreading a lot of good this week. She also appeared on an episode of America's Next Top Model to address the serious consequences of bullying.

Check out Demi's PSA and tell us what you think. You can also tweet to win a bracelet inspired by the 18-year-old star.