Take Paul Shaffer of “Late Show with David Letterman” fame, who’s quietly and loyally supported the host and his amazing array of guest for the last 27 years.

The Canadian musician and composer – he co-wrote the campy gay club staple “It’s Raining Men” with the late Paul Jabarra – has just released his autobiography, “We’ll Be Here for the Rest of Our Lives: A Swingin’ Showbiz Saga.”

Shaffer, who CNN called a “walking Wikipedia of rock ’n’ roll history,” got his television start with his dead-on impersonation of ’70s rock impresario Don Kirschner on “Saturday Night Live” and confirmed to the network that he was offered a role on Jerry Seinfeld’s iconic sitcom.

“Just to be clear, I was offered the role of Jerry Seinfeld’s sidekick,” Shaffer explained. “He had three sidekicks, and I had a feeling mine might’ve been [George Costanza]. And any regrets? Well, I mean it was only the most beloved show of all time. … Truthfully, though, I would have missed the opportunity to play music.”

So instead of delivering lines about things like soup nazis and marble rye bread Shaffer has spent more than a quarter of a century delivering low key comebacks to Letterman and slipping in hilarious music cues to play guests onstage, which he told CNN is often a group effort.

“We think of them in the rehearsal before the show,” he said. “I have about 15 minutes, and I often throw it open to the floor. And by the floor, I mean the musicians, the band [the ‘Late Show’s’ CBS Orchestra members]. And I say ‘Who has an idea for this?’ And I pick the one that I like the best.

“[Once we] had a new actor named Aziz Ansari, and one of the guys in the band says, ‘I’m Sorry’ [referring to the Brenda Lee song]. So we did it, and it cracked Dave [Letterman] up so I knew that I got my one laugh – and the most important laugh.”

Read the rest of CNN’s interview with Paul Shaffer here.

Friday, October 16
Dan Levy, Chris Franjola, Loni Love – “Chelsea Lately” – rerun
Tim McGraw – “Late Show with David Letterman”
Eddie Izzard – “Late Night with Jimmy Fallon”
Eric Church – “Jimmy Kimmel Live!”
Toby Keith – “Late Late Show with Craig Ferguson”

Saturday, October 17
Kenny Chesney – “Austin City Limits”
Shakira – “Saturday Night Live”

Monday, October 19
Aaron Carter & Karina Smirnoff – “The Ellen DeGeneres Show”
Carl Reiner, Heather McDonald, Randy Sklar, Ross Mathews – “Chelsea Lately”
Rosanne Cash – “Late Show with David Letterman” – rerun
Rod Stewart – “The Jay Leno Show”
Deon Cole – “The Tonight Show with Conan O’Brien” – rerun
Tracy Morgan – “Late Night with Jimmy Fallon” – rerun
The Used – “Jimmy Kimmel Live!” – rerun
Mat Kearney – “Last Call with Carson Daly” – rerun