Of salutations and respect

My father once asked us siblings over dinner, he said "Is it rude if you hear a stranger with aku-kau?". Promptly I responded it depends on the person's age. If a much younger person addresses my father with 'kau' I would say he is rude. Then my father continued saying he had known that person since before we were born, and hasn't met him in ages, and still was addressed with aku-kau, a sign that the friendship between them has not deteriorated since as well as how friendly the other person is in general. 

Some readers may not be familiar with our culture so a little background is due : In Malaysia, particularly in Sarawak, there are 3 main ways to address yourself and the person you're talking to/with corresponding with I - you. Formally, I in Malay is saya, while you is awak. Between relatives, or in situations where there is a big gap between age, or to show affection, saya is replaced with kamek and awak is replaced with kitak. Among friends and peers, it is replaced with aku and kau respectively. 

There are no ground rules regarding the use of these pair of nouns, some mix and match according to their own preferences and origin i.e. aku-kitak and saya-kitak. As a listener, you can place an assumption of how close the friendship between the speakers - then again it is not definite. Closest example I can give is me and my best friend still address each other with saya-awak even after almost 20 years knowing each other. 

As far as generalization goes, among same gender conversation, aku-kau is preferred to indicate a close friendship but not intimate, kamek-kitak is used cross gendered or when addressing a person much older or younger than you are, and saya-awak in formal situations. 

As for myself, (and I believe most will agree) I go with the flow. As a native speaker of the language and dialect, it comes naturally to me to know which addressing noun to be used in what situation. It will be a little awkward the first few times, but usually, once it has been used a few times with the same person, it sticks and very rare changes to a different pair of nouns. Interesting, isn't it?