Source: The Simpsons, Episode 98 -- "Bart Gets an Elephant" (Season 5, Episode 17; Production 1F15; March 1994)
In this episode, Bart wins an elephant in a radio station contest and names his new pet “Stampy.” After running out of food for the elephant, the Simpsons take Stampy to the local “tree place” (the Springfield Arboretum) so Stampy can eat his fill of leaves and bark. A bird lands on Stampy’s back and starts grooming the elephant (a standard symbiotic relationship in the natural world). From this, Homer gets a typically bright idea: obtain his own bird, which could then provide Homer with similar grooming services.
In the next scene, a bird is atop Homer's head, picking at the two hairs on Homer’s scalp. Marge walks in, notices the bird, and excitedly tells Homer there’s a bird on his head. Homer responds, “I know. He’s grooming me.”
Then Homer contentedly moans, “Mmm… elephant fresh.”
This is especially humorous to anyone who has ever owned a bird of the parrot family (e.g., a parakeet or budgie) as a pet, because this is what these birds naturally love to do!