This is fun.
Called my paternal grandparents Mama Shelton and Papa Shelton. Why? I dunno. That's what all the other grandchildren called them (Papa died on my 1st birthday, so I guess I never technically called him anything).
Called my maternal grands Papaw and Mama. I know most folks call their mothers Mama (or Momma?) if they call anybody Mama, but we picked it up from our mothers calling her Mama and it just stuck. (For that matter, I called my mother Mother and my aunt .... Sister!! Because that's what Mother called her!

) (Side note: Come to think of it, all of my mother's siblings had odd nicknames. Her brother Warren we called Uncle Buck, died at age 51 from literally drinking himself to death. Her brother Lois we called Hashi Baba --- I still don't know why --- died at age 39 when he got drunk, passed out with a cigarette in his hand and burned his house and himself with it. And her brother Charles was called Buddy Charles because that's what my oldest brother called him, but he died in a drunken high-speed car wreck on the week of Christmas in 1960 at the age of about 22 and I never knew him. See a trend? Bummer note for this otherwise cheery thread!!!!)
My daughter calls my dad Papaw Gilbert and calls my wife's mom Mammaw (pronounced Mam maw, not Mom maw). If Mother had lived long enough for my daughter to learn to talk, she would call her Mammy (that's what my oldest brother's daughter began calling her 35 or so years ago, and all her other grandchildren called her). My wife's dad was called just Papaw (pronounced Pap paw, not Pop paw).
Human government bears the same relation to hell as the church bears to heaven. (David Lipscomb, On Civil Government, 72).