One clever Easter egg appeared regularly for the entire first two seasons. Production company Braniff featured a jaunty 12-note tune, played on a xylophone, over the graphic that closed each episode. At the time, few people outside of Colorado—where Parker and Stone went to college–would have known what it was, although it might be a little more familiar now.
It's the melody from "Shpadoinkle Day," a song featured in Parker and Stone's first film Cannibal! The Musical, which was completed in 1993 and released the year before South Park's debut by the infamous Troma Studios. The movie started as a project for Parker and Stone's film class, and while they never finished the class, they did finish the movie. It would go on to considerable cult success upon re-release—mostly due to South Park's notoriety, but also because it's hysterically funny.
Also, in the South Park movie, the doctor's discovery of a baked potato in the microwave when attempting to zap Kenny's heart is a sideways reference to the song and its line, "my heart is full as a baked potato." The duo are obviously proud of this tune, and with good reason; if everyone started every day by listening to it, the world would be a much more shpadoinkle place.
