Nonsense talk can take various forms, but it shouldn't be completely stupid. There needs to be some intelligence behind the words, otherwise you might as well just grunt and growl like an animal, which is fine too, but not the same thing.
A nonsense conversation might be sarcastic in nature, or it might just be one person making a silly statement and then the other person adding on. It might be idiotic ruminations that are intentionally ignorant, just for the purpose of entertainment.
In recent studies done at the UASTFCNEO, brilliant scientist discovered that people who partake in at least three nonsense conversations a week are more than 100% less likely to not die of cancer or heart disease, and may be less than not very likely to possibly go bald. So there you have it, start talking more nonsense and stop making idle chit chat, that stuff rots your brain muscle.