I've heard it recently, and I believe it's native american.....
What does yatahey mean?
Looks like it means "Hello and welcome" in Navajo.
Here's a link from a VERY authoritative source -- "some guy": Google Groups thread
Dave of the "Ya Ta Hey!" class
I think it depends on the way you pronounce it, whether it means "hello" or "Kiss my A$$." Do you have any Indian friends that you can ask?
It's Dine (Navajo) greeting for hello...
I think it is translated to mean
Is it Good?
to which you would reply
which I think means yes
Plummet Totah Denache (I think)
Plummet (from where three rivers meet)