We call my grandmother Gummy. Madame Gumball, if you are my father and are feeling contrite. Gummy is derived from my sisters’ inability to pronounce grandmother as children. Or grandma. Or anything really. They are thus credited with the creation of the masterful name “Gummy”.
If our family has a matriarch, its most definitely Gummy. We all adore her but are frightened of her “jokes” about how when she gets a cane, she will hit her grandchildren with it to keep us in line. She is probably kidding. We don’t know.