The yawn comes from Woody Woodpecker, the long-running cartoon woodpecker created by Walter Lantz, and appears at the beginning of the episode Cabin Fever from The New Woody Woodpecker Show, where he is woken up and responds with an exaggerated stretch of tiredness. Short cartoon reactions like this travel well on soundboards because they are instantly recognisable even without the picture, and this one has been kept in circulation by creators who need a quick, funny signal for sleepiness. Its appeal is simple: one familiar voice, one clear feeling, and no explanation needed.