Two major country stars have given in and joined the ranks of Twitter!   Carrie Underwood joined Friday with her first tweet, "Hello Twitter world!"   Since then, she's been very conservative, talking about hubby Mike Fisher's hockey team the Nashville Predators and going to a fashion show.  Trace Adkins, on the other hand, has taken to Twitter like Blake Shelton!   Tuesday, the big guy was at Vanderbilt University Medical Center in Nashville to have some kidney stones removed, wearing a hospital gown that let it all hang out.   Nice badonkadonk Trace!   "@ Vanderbilt having kidney stones busted. No big deal,"  he wrote.   So, what made Trace break down and join the Twitter world?   On Monday, in a video to fans he explained that his  flip phone had broken, so he got an iPhone and decided to learn how to use Twitter because he thought it’d be a better way to interact with fans during his Songs and Stories Tour.    "I have surrendered.  And I’ll start tweeting. Let the games begin," he said in a video on Whosay.   If his early tweets are any indication, he is going to be someone you need to follow!  "Trinity and Brianna have sore throats. Don't want to get it. Sending them to China to get jobs."    In the mood for some badonkadonk?  Thought so!