[Ger-Poland-Volhynia] Figuring Relationships

[Leo Sonnenberg]

I recently received a list of ancestors on my father's side back to 1790 
from a cousin in Germany. I was surprised to see that my grandfather on 
my mother's side was also on the list.
My mother is a great granddaughter to the common ancestor and my father 
is a great great grandson to the common ancestor. I am both a great 
great grandson through my mother and a great great  great grandson 
through my father.

My questions are -  A. what cousins are my parents to each other and B. 
what am I to my distant grandfather?  How would I classify myself - a 
two great grandson or a three great grandson? So who am I?

Also, does this situation occur very often?

Any definition of my relationship to my distant grandfather is welcome 
(including any jokes).

Leo Sonnenberg