Kenny Chesney went to East Tennessee State University, which is where I went, though Kenny was about 10 years after me. He did pledge Lambda Chi and get this -- my nephew was Sig Ep president the year Kenny rushed and they did not give him a bid! See, it can happen to anyone.
Kenny is listed on Lambda Chi's National website under Prominent Members. He also mentions Lambda Chi in the song "Keg in the Closet." It doesn't sound like he has left the organization, but hopefully a Lambda Chi can confirm.