Peter Mark Andrew Phillips, born 15 November 1977
Your first cousin's grandson is your first cousin twice removed.
The grandson of your first cousin and your grandson are third cousins to eachother.
Your grandson and your first cousin are first cousins, twice removed.
Your first cousin's grandson son is your grandson's third cousin. Your second cousin's grandson is your grandson's fourth cousin. Etc., etc.
Benjamin Harrison was the first, and only, grandson of a formal president to become a president. He was the grandson of William Henry Harrison.
Your first cousin's grandson is your first cousin, twice removed. Your second cousin's grandson is your second cousin, twice removed.
Your uncle's grandson is your first cousin once removed.
Your niece and one of your grandson's parents are first cousins. That makes your niece a first cousin once removed of your grandson.
Your grandmother's first cousin's grandson is your third cousin.
Your grandson and your first cousin are first cousins, twice removed. Your grandson and your second cousin are second cousins, twice removed. and so forth.
You and your uncle's grandson are first cousins once removed.
Your grandson and your nephew are first cousins, once removed.