This video of a penguin being tickled was uploaded on April 15h. In three days it was shared on facebook 1900 plus times, been the subject of 335 tweets and who knows how many blog posts. Suffice it to say, people love penguins. Ones that laugh, even more so.
http://www.youtube.com/watch?v=GnxGZ9jeuP8&feature=player_embedded