I was watching a Japanese series recently and a young man 25~30 years old refers to his parents as otou and okaa.
This took me by surprise as I've never even considered that that could be done. But it makes sense, it's just dropping the san which is a kind of a title/honorific.
Anyway one would assume that say otou is very very informal to the point of being rude and disrespectful or at least just young people trying to sound cool in front of their friends. But the young man in the series was actual quite a polite and cultured young man and it seemed strange to me that he would use it.
How often are otou and okaa used in what contexts etc ?