The meaning of the Spanish phrase, is not grandmother?
Not being a grandmother in Mexico doesn't mean being shameless or having a conscience.
Juan: Pedro's grandmother is not. Get involved with women just to bring them down.
(Pedro is not ashamed. He only goes out of his way to take money from women).
Another common term used for this purpose is meaningless. (She doesn't have a mother).
The meaning of
No grandma literally doesn't mean grandma,
In Mexico, it is easy to say this sentence to the nun again (mother), we both use it in different ways ...
There is no grandmother in this movie
This movie is really good ...
There is no grandmother in this car
This car is amazing.
George has no recurrence (or grandmother)
This means that George doesn't care about anyone, he does or does something (comments, actions, studies ...) without thinking about others ...
George has no grandmother
This literally means that George does not have a grandmother.
In other contexts, this means that George sang / bad / nanny / stupid / very good etc ...