This may not necessarily be my choice for the best word ever, but it is rapidly garnering acclaim across the Internet. The word that I am referring to is "Asshat". And this guy believes that it is the best word ever.
Other sites have jumped on the Asshat bandwagon.
If you look up Asshat on Google, you will find an astonshing number of references to this word across the Internet. It has become so popular that it has found a place in the catalogue of common lingua, the Urban Dictionary. Various definitions exists for Asshat, but it is clear that it is some kind of swear to those who upset you.
Already URL claimed, Asshat is clearly an evil word, and should be used only when appropriately warned.