Farm Yard Philosophy ?

Why do most people start giggly an uneasy laugh when they see a farm animal appear on TV ? What are they scared of ? Ive noticed this so many times, and adverts also seem to perpetuate this comedy image. Do people subconsciously feel as though they are maybe no more than such animals underneath all their outwardly sophistication ? There is definitely something going on here as an image of a cow or sheep is not naturally comical.