I called my grandmother Granny. I only ever really got to know her of all my grandparents. I met my grandfather on my moms side for the first time when I was like 15, so I have no idea why to call him.

My nieces/nephew call my mom Nanny Bobbi and my dad Grampie Andy. My niece calls one of her other grandmothers Mammie (don't know hwo to spell it...maam-E)