The good folks at Google have a great sense of humor. Ever since the launch of GMail on the 1st of April, and the subsequent April Fool jokes, we are always guessing what hidden joke lurks in each of the Google products. Here are some of them that I have found, you can check them out too!
I am also including some of the outputs, which you can try by yourself as well!
Do a Barrel Roll
Search this term in Google search, and watch the fun as the search queries take a tumble, and literally does a barrel roll!
Askew
Search this term in Google search, and see the screen go askew!!
Ascii Art
Search for this, and the Google logo shows you what Ascii Art is all about!
Recursion
Have you noticed that when search on Google, if you do typographical mistakes, Google corrects you by asking you “Did you mean <corrected spelling>”. Try searching recursion on Google!
There are more such easter eggs in Google, but they are time bound (for example searching football during the Soccer World Cup would give you an interested Pagination navigation on Google).
As a bonus, try this out in your Google Reader – up up down down left right left right b a b a (and beware of the ninja!).