Maybe you already noticed in the last couple of years that Google is celebrating your own birthday with a special doodle. When the magical moment of your birthday has arrived then go to the homepage of the search engine and you will see the logo, when hovering over the image with your mouse the the text ‘Happy Birthday [Frontname]’ will show, after clicking on the doodle there’s no search query like with normal doodles but in this case your own profile on Google+ will open instead.
Google shows the doodle based on the date in your profile and ofcourse the logo is only shown when you are logged in. Tis started in 2010 and recently Google renewed the logo I noticed today after opening the homepage, the new version has more cakes and firework then the previous version, both versions below.
In any case it´s a nice way to congratulate users with there birthday, so thanks Google!