O'Brien took Ethel by surprise when he hauled her into the audience of mostly young children, Hahn said. Ethel panicked and started running up O'Brien's torso.
"When he handed her back to me we realized what had happened," Hahn said, adding that O'Brien joked about it and pointed to the wet spot for the camera.
Ethel is sharing tonight's stage with several reptiles, all from Reptiland in Allenwood, Pa. They include a grapefruit-sized African bullfrog, a cantaloupe-sized toad and a 15-foot python.
Peeling, who owns Reptiland and is known nationally as a reptile expert, has been doing TV appearances for several years on shows such as "Live with Regis and Kathie Lee" and NBC's "Tonight Show with Jay Leno."
Tonight's "Late Night" program was taped in New York on Monday and airs after midnight.
"I was more afraid of New York City traffic than I was of doing the show," Hahn said of her first trip to the Big Apple.
She said the whole thing was hectic because she left Maryland before dawn on Monday, drove six hours to New York and searched for a parking space around Rockefeller Center for 30 minutes.
After trudging through several pedestrian-packed sidewalks - Ethel in tow - Hahn said she and Peeling waited two hours at NBC's studio before being called to the set for five minutes with O'Brien.
"Five minutes go by in a blink," Hahn said, adding that, however brief, the appearance was a real treat.
But Peeling said O'Brien isn't as comfortable with animals as other talk show hosts. Leno, for example, goes beyond showing off exotic creatures and allows some air time for an educational discussion, he said.
"My sense is he's not really an animal enthusiast," Peeling said of O'Brien.
Both Peeling and Kahn have been lifelong caretakers of the wild.
Kahn's family has owned Catoctin's 56 acres of wildlife preserve and zoo since 1966. The zoo is about 12 miles east of Hagerstown on U.S. 15 and features an 11-foot-tall Grizzly named Griz, a 575-pound tortoise named Tank, mountain lions, jaguars, waterfowl and regional wildlife. Reptiland is 135 miles north of the zoo, also on U.S. 15.