Rush Limbaugh, the most successful conservative radio personality ever, must come clean over allegations of drug abuse, or he's toast. I say this sadly, since I'm one of Rush's 23 million fans. Allegations that he illegally obtained and used huge amounts of addictive pain pills like OxyContin, the "hillbilly heroin," can't be papered over with "let's stick to the issues," as Rush told his listeners yesterday.