Why is George W Bush called "Dubya"?

Why is GWB called “Dubya” ?

Something to do with his middle name/initial “W” and the way a Texan might pronouce “w”. I think.

Jenn, nak

Exactly. Kinda has a country twang to it. I dont think its derogatory, and Texans would think of it as a term of affection. Yankees and Democrates (Generally one and the same), however, may use it spitefully