http://www.google.com/trends?q=birthday
The whole graph runs usually fine until at the end (during may 2006) it goes suddenly up then down agn .. what is this?

I looked more closely and the date was 21th of may as seen here:
http://www.google.com/trends?q=birthday&ctab=0&geo=all&date=2006-5

Any other keywords that drew attention?
Thanks for the icon , Philipp!!

Looks like its American as your second link shows entirely American cities where as the first is more varied
San Diego, CA, USA

2. San Francisco, CA, USA

3. New York, NY, USA

4. Irvine, CA, USA

5. Seattle, WA, USA

6. Sydney, Australia

7. Los Angeles, CA, USA

8. Atlanta, GA, USA

9. Philadelphia, PA, USA

10. Chicago, IL, USA