Why is Murphy called Grandpa Meng?

Although I'm not sure why Morphy has the title of Grandpa Meng, I think it's just someone else's nickname. Perhaps what he said was accepted by many people, so others thought that only those elders would say such things, so they called him Grandpa Meng. Suddenly, I found that sometimes nicknames are just a whim in the classroom, but others will laugh subconsciously if they are called too much. It's not unusual to say that beggars like Grandpa Meng have nicknames, and if they are famous at a certain age like those stars, most people won't say that uncles only call them big brothers. That's just a title. According to his age, you can be your father, but you can't call him uncle or anything in front of him, which will make others feel uncomfortable, so you will subconsciously call those older people big brother.