What does it mean to sell out? When, if ever, is selling out OK? (It is.) (Is it?) (Sometimes.) We take a long look at musicians who sold their music for advertising. Even though artists sell out all the time, we managed to find a few surprises. Like a soda jingle performed by a band that made sure it never made the air. And a 2 Tone classic used to sell toothpaste. And did you know the Moody Blues sang a jingle for Coca-Cola? They really did.