There was Jimmy Stewart movie - Mr Hobbs takes a vacation. One scene has his grown daughter show up with her family, and her kid is crying doesn't want to get out of car. And she tells him, "Don't be scared darling. That's Boompa. You love Boompa." And Jimmy says, "Boompa?", and she says, "That's what he calls you".
And I decided right then and there when I saw that movie but that would never happen with me. And when my daughter told me she was pregnant, I told her that was wonderful. And I was Grandpa.
Them kids never had a choice. If they called me something besides Grandpa I didn't answer.