I believe it's written "ODZ DZO DZI" but sounds more like "OD ZOD ZI".
Alexander Chamberlain, in his work "The Child and Childhood in Folk-Thought", had this to say about war cries in college fight songs...
The "college yells" of the United States and Canada
offer an inviting field for study in linguistic atavism and barbaric vocal expression.
The New York World Almanac for 1895 contains a list of the "yells"
of some three hundred colleges and universities in the United States.
Out of this great number, in which there is a plentitude of "Rah! rah! rah!",
the following are especially noteworthy....
He goes on to note some other examples and then says:
The palm must, however, be awarded to the University of North Dakota,
whose remarkable "yell" is this:
"Odz-dzo-dzi! Ri-ri-ri!
Hy-ah! Hy-ah! North Dakota!"
Hardly could the ancestors of Sitting Bull and his people
have suspected the immortality that awaited their ancient slogan.
Hope this helps.
Dave