My Pa looked and acted a great deal like Jimmy Stewart. Jimmy did a movie called “Mr. Hobbs Takes a Vacation” wherein his grandson called him “Boom-pa”
My brothers and I would tease Pa by calling him Boom-pa all the time. He would protest but I knew he secretly enjoyed it.
Grandkids do come up with some doozy names for grandmas and grandpas. My own mother was called “Da” by the first grandchild and was known by that by the following 12 over the years. It became easy for us to refer to our own mother as “Da” when talking to the kids and it became a habit to us.
Our grandson when very small called his grandpa, “Crapa” as that must be the way it sounded to him - giving us all a chuckle. I wanted to be called Grandma and I am called Grandma - no cutesy names for me. I know grandmothers who actually tell their grandchildren what they want to be called and it’s always a “cutesy” name. I guess so they don’t feel old. I waited long enough to have our daughter and long enough also to become a grandmother and I’m not giving it up!