One Day Mafatu: Soon; eventually; Used to declare your intentions are on track, and will happen…just not today.
A promise of future vengeance for a real or perceived wrong;
(I’m not too sure of the origins, but Mafatu was the main character from Armstrong Sperry’s growing up novel, The Boy Who Was Afraid.)
I know I should be saving my money but… I will. One day mafatu.
Yeah you wait there boy – one day I gonna smack your face properly saraga. One day Mafatu…
#1 by wendy on October 29th, 2009
Hey, that is a very old book! I was teaching that in English way back in the 60s – perhaps at Penang Sangam High School. Is the book still being taught in Fiji?
w.
#2 by Wilson on October 29th, 2009
Yep – loved that book
Hmmm don’t know if its still in the curriculum – i dont think so though 
#3 by Kania Tiko on November 5th, 2009
I think your definition is wrong, isn’t it really about a promise of future vengeance for a real or perceived wrong?
#4 by Wilson on November 19th, 2009
Hmmm good point. While I’ve never really used it that way, I have heard it like that. I guess it could come down to a promise that for sure, something’s going to go down in the near future. Slangs are kinda subjective
I’ve added your version in the post.