Well one of Leno's producers, Dave Berg, is dishing all the juicy secrets in a new tell-all book. And we're talking juicy -- like how much stars wanted to be paid to come on the show and which celebrities were major divas.
First up, though, Berg spoke with the "Fox & Friends" anchors about who he considered the "riskiest" guest to have on the show. And it turns out it took some effort to get him there.
"That guest happens to be a very good friend of mine. And that's Dennis Rodman. He was perennially late. He would never get in his limo. He lived 50 miles away, but I had to bring him to the studio in a helicopter. But he was still late!"
Somehow this doesn't really surprise us. Now, actors are often expected to appear on shows and talk about their latest projects.
Berg writes that actress Helen Hunt had a pretty hard time of it, and she refused to come back on the show for 14 years after a producer talked to her about it.
Berg believes it's a toss-up as to who was the biggest diva ever to come on the show: Teri Hatcher of "Desperate Housewives," or singer and fashion designer Jessica Simpson.
According to the New York Post, Simpson refused to come on the show unless Leno's crew coughed up the $18,000 required to have her hair and makeup done. And when Hatcher got bumped from the show in 2009 so President Obama could make an appearance, Berg says her people told him a Louis Vuitton handbag would make a really great apology gift.
Hatcher ended up getting a bouquet of flowers instead.
Several times, though, some persuading was in order. To get President Bill Clinton to appear on the show for an interview, they had to send him a $12,000 tandem bicycle in 2004.
Clinton sent the bike back as his wife, Hillary, was a U.S. senator at the time and couldn't accept expensive gifts.
He also never went on the show ... maybe because Leno made more than 4,000 jokes at Clinton's expense during his tenure, according to the Los Angeles Times.
Berg's book includes lots of other humorous anecdotes about Jesse Jackson having terrible stage fright, Eddie Murphy requiring eight cream soda drinks in his dressing room, and Christian Bale refusing to come on the show after being asked personal questions like where he grew up and what his first acting job was.
As for the other funny stories? Guess you'll just have to check out the book.