Youtube has new easter egg "Harlem Shake". Search as "Do the Harlem Shake" on youtube and watch the youtube's Harlem Shake Dance.
"The Harlem Shake is an Internet meme in the form of a video of various groups of people performing a comedy sketch accompanied by a short excerpt from the song 'Harlem Shake'. As a meme, the video was replicated by many people, using the same concept, and this rapidly led to it becoming viral in early February 2013, with thousands of 'Harlem Shake' videos being made and uploaded to YouTube every day at the height of its popularity." - Wikipedia
When you search 'Do the Harlem Shake' on youtube, it will shows the results. Within few seconds, Youtube Logo will start the Harlem Shake Dance. After few seconds, whole page will start dancing.