Well just for you, that in a way is what YAHOO stands for..

Yet Another Hierarchical Officious Oracle

http://docs.yahoo.com/info/misc/history.html

http://en.wikipedia.org/wiki/Yahoo

So that is what the full form of Yahoo is. Had it in my mock cpc. I just remembered the yet another part at that time.

Abbreviation of Yahoo is something that people in general don’t come across with. Mostly will thing that its the general euphoric cry. But its not. Read about it more in the given above links.