"Hey Cow" is a Sesame Street song.

The song, once described as a "Simon-and-Garfunkel-inspired tune"^[1], was used to accompany one of the show's first animal films. The 6 minute 30 second film (later edited for time) featured the song throughout the entire piece, with the lyric "Hey cow, I see you now" often repeated, as well as references to the cow's home of "shady trees and sunny skies".

Sources

1. ↑ Feinstein, Phyllis All About Sesame Street introduction