My mother's side--Grammy & Boo. Father's side--Grandma (Name), Grandpa (Name).

grandmother - Mother
grandfather - Gramps

Oma and Opa (Dad's parents)
Nana and Papa (Mom's parents)

I'm not very exciting:

Maternal Grandmother: Grandma Rose or Grandma Rosa (just b/c I didn't learn to say her name right until I was like 14 lol)
Maternal Step-Grandfather: Grandpa

Paternal Grandparents: My sister nor I never met them, so we never had names to refer to them with. Oh occasion, it would be Grandpa Milo and Grandma during conversation, but that's really it.

Ma'am and sir.

I was ahead of my time.
 

My paternal grandmother = Gaga