As Letterman wraps up over the next few weeks, he has many big names coming on The Late Show.
Jungle Jack Hanna arrived in New York City Tuesday night ahead of his final appearance on the Late Show.
10TV had the opportunity to sit down and speak with him when he arrived in the city and he shared how he gets himself ready for stepping on the stage at the Ed Sullivan Theatre.
Hanna said, "I go to the basement of Ed Sullivan theatre, in basement where people leave me alone. They think I'm going to the bathroom, I'm not. I'm concentrating, doesn't sound right, concentrating in bathroom!"
Then, Hanna said he takes a walk, "And then right before I go on, I go upstairs and check all animals and Brian or Suzi or Steve will tell me, 'Jack maybe you want to say this about the animal,' and they give me the order of the animals."
After appearing on the show dozens of times over the past 30 years, there's one thing few people know about how Jack and Dave interacted off camera.
"Everybody says, 'Jack you must be his big buddy,'" Hanna said. "I've never talked to David Letterman in 30 years before or after the show, ever."
That is until a recent show where Jack brought two hyenas to the Ed Sullivan Theatre.
"He comes to green room with Harry, his 12-year-old son, most unassuming kid," Hanna said..
"He comes over and said, 'Dave wanted to see what was going on.' I just about fell out of my pants," he said.
Jungle Jack said it's these unscripted moments that make the magic viewers see at home.
"They used to write notes for him, that was stupid. I could see after four or five years. I don't write no more notes, he don't read anything I write him," Hanna said.
Jack says there was one defining moment that sealed the bond between him, Letterman, and his family.
In 1997 when Jack's daughter Julie underwent surgery at Nationwide Children's Hospital to remove a brain tumor, Hanna said they returned to her room after surgery and found 40 roses from Letterman. "With his own hand written note, 'Prayers for you, I hope Julie gets better,'" Hanna said.
So as Jack prepares for Wednesday's final appearance, he hopes it won't be the final bow for the Columbus Zoo on the national stage.
You can watch Jungle Jack's last appearance on the The Late Show with David Letterman Wednesday, April 29th right after 10TV News at 11 p.m.