Comedy geeks and aspiring humorists, prepare to freak out.

Vanity Fair writer Mike Sacks manages the seemingly impossible: Squeezing funny, revealing anecdotes out of notoriously difficult-to-interview giants of the industry. Interviews include former David Letterman head writer Merrill Markoe, Ricky Gervais’ secret weapon Stephen Merchant from “The Office,” Allison Silverman, head writer for “The Colbert Report,” and Harold Ramis, who talks about “Animal House” and “Groundhog Day.”

It’s like a DVD commentary track — but with answers to questions you actually want to hear.

Director Ramis is particularly candid. “I didn’t like Saturday Night Live that much,” he says, when asked why he never joined Lorne Michaels’ writing cast.

Contemplating whether the initial commercial failure of “Caddyshack” may have driven one of the film’s writers, Doug Kenney, to commit suicide, Ramis says: “Doug [who died in a hiking accident] . . . was very disappointed with the movie, but I’d hate to spend the rest of my life thinking that I directed and co-wrote the movie that killed Doug Kenney. We were so arrogant and so deluded and maybe deranged that we thought everything we would do would be as successful as ‘Animal House.’ And Doug knew only success.”

Merchant, meanwhile, gives his take on the “happy ending” of the BBC original version of “The Office.”

“It almost hits a pleasure center in the brain, like a good melody. When you listen to a good song, you don’t say, ‘I can’t believe it! Another song with a chorus and a verse and then the chorus again! What a cliché!’ No, you think, That’s a great song. It’s very primal.”