By Kayla Kibbe Playboy’s darkest secrets are set to be revealed in A&E’s much-anticipated new docuseries, Secrets of Playboy, which premieres today. But while one may readily expect all manner of sex, drugs and debauchery to have gone down within Hugh Hefner’s infamous empire, Playboy insiders interviewed for the series allege certain acts of depravity that are shocking even for a brand synonymous with sex and scandal. According to some sources, the hard-partying men of Playboy’s heyday — including Hefner himself — sought increasingly extreme sex acts to sate their growing sexual appetites, in…