As a teen, actor-comedian Denis Leary learned about rock'n'roll drama firsthand. "A bunch of Boston friends became rockers, so I was always backstage or hanging out at their rehearsals," he recalls. "Their arguments were always hilarious to me." Those experiences inspired Sex&Drugs&Rock&Roll, his FX show that debuted July 16, which follows the up-and-down exploits of an aging frontman (played by Leary) reuniting with his former band. The 57-year-old appraises real-life musical reunions, from the euphoric to the cringe-worthy.