some Arabic formal words can be strange for Arabs as well.
That's right.Once when I told "Swaff-al-'Aashir" (Class-10) to a Saudi,he didn't understand.Then I told "Swaff Ashara".
Yeah.Arabic slang and accents differ from one region to another even within the same country.
I remember some Kuwaiti customers in my father's shop some few yrs ago. They asked "Cham Hadha?" instead of "Kam Hadha?" (ie,what does this cost).
I was a little confused with that.