"Nothing's the matter." boy, was i getting nervous. "The thing is, i had an operation very recently."
"Yeah? Where?"
"on my wuddayacallit - my clavichord"
- an excerpt from 'The Catcher in the Rye' by J.D. Salinger pg87.
waddah! is a standard greeting or hearty hello to someone, or something just to wake people up and annoy them. It's a slight variation on wasssupp! except dumbed down even more so. Waddah! was created by smiddeh.