Dr. Sam Livingstone appeared in a Sesame Street sketch in which Ernie and Bert look for him the jungle. When he was found, he introduced himself as "Sam Livingstone, Jungle Doctor." Ernie's sole aim in the expedition is to be able to ask the good doctor Bugs Bunny's trademark query, "What's up, doc?" As everybody cracks up, the doctor remarks to the camera, "This jungle's full of jokers!"
His name is derived from the Victorian explorer David Livingstone.