Whatcha?
-Whatcha doing Hugo?
-Nothing.
-How can you do nothing?
-Easy - just stop doing something.It is a conversation between 2 kids.
What 'whatdra' mean? It is not used often, I think.
IS it an American word?It means "What are you doing?" Whatcha/Wotcha is an approximate phonetic spelling of the way "What are you" is informally pronounced.
In England, "Wotcha, mate" would be an informal greeting.
I think the English expression "wotcha" or "wotcher" comes from a different root than "whatcha" in this sense. I found out from this site that "wotcher" is short for "what cheer" and originated in English pubs. (Browse the archives under "wotcher" for that info).