In this movie, it is said that Feng Cuifan always likes swearing. He felt that he couldn't resist and didn't want to do it, so he went to a psychologist. The doctor told him a way. If he really wants to swear, he will change it to a fruit name, such as banana, bara, grape, cantaloupe and so on.
Anyway, I think this drama is quite classic, which is probably the source of bananas.
Hmm. How interesting