It's easy when you have grandparents who are from two different cultures. My Italian (Sardinian) grandparents were Nonno and Nonna, and my Ukrainian grandparents would have been Baba and Dyido (hard to spell the pronunciation). However I never knew my Ukrainian grandparents, because they are both long dead, and my Sardinian grandparents lived very far away. Actually, I am completely without grandparents now, since my last surviving grandparent, Nonno, died last fall.
On a brighter note, due to my lack of locally available grandparents, I borrowed a great-great aunt and uncle, who happened to be close to our family, and called
them Gramma and Grampa. They fit the role quite well. My "Gramma" is now 96 years old and until last year or so, was going to aerobics classes three times a week at her seniors' residence!
About six years ago, when she was still living in her 12th floor apartment, she walked up to her apartment one day when the elevator was broken. (Okay, she rested every few floors - but still!)
