Four sponsors have severed ties with Rush Limbaugh’s radio show after the outspoken host called law student Sandra Fluke a “slut” and a “prostitute.” National advertisers LegalZoom, Quicken Loans and Sleep Number along with West Coast ad buyer The Sleep Train announced this week they were pulling all advertisements. “We don’t condone negative comments directed toward any group. In response, we are currently pulling our ads from Rush with Rush Limbaugh,” Sleep Train wrote on Twitter. Sandra Fluke, a Georgetown Law Student, was thrust into the spotlight this week after Limbaugh called her a “slut” for her stance on a new insurance mandate...