Well, his accent is really "sterotypical Jamaican" unless you're one of those people who believes in sterotypes IMHO. I mean, how many people have talked to a Jamaican? They don't talk like that.
Saying that, as far as "backwards speak". I think Lucas just wanted everyone to have f-ed up ways of talking and that might have associations. It's kinda sad that we can label a whole group of people as being like Gungans!
I am the definition of your defeat.