on a side note despite the english dub version.
dattebayo does not mean belive it.
dattebayo has no realy meaning other than its a kinda of phrase that
children add to the end of their sentances.
the english dub generealy translates dattebayo as belive it:
1. because otherwise narutos mouth would be moving and there would be no sound
(they do not reanimate for engdubs just put in different
words)
2. its what the creaters of the engdub version of naruto
best reflected the childish connotations of dattebayo
if you watch the japanese and engdubs at the same time there are
alot of times in the japenese where naruto says dattebayo or -tebayo and there is no reference to it in the eng dub