A U.S. Midwestern term with Italian ancestry. Means: A man with a huge cock who knows how/when/where to use it. Very giving, unselfish in nature. Will stick it in her puss, mouth or butt. Not only because he wants to, but because he has to.
"I know I should have been with my husband on our wedding night, but he was GRZ after all."
one who uses cheese whiz as lubricant
"Wow, that grz is really goin at it with that cheese whiz"