It is a term of endearment used by older siblings and sometimes even by close friends or acquaintances to refer to a younger male.
Here are some additional points to remember:
* It is not a surname. While some people may use "Maung" as part of their full name (like "Maung Kyaw"), it is not a family name.
* There's a female equivalent: The Burmese word for "younger sister" is "Ma" (pronounced "mɑː").
* It's a respectful term: While it's not a formal title, "Maung" is a way to show respect and affection.
If you're unsure if it's appropriate to use "Maung" when addressing someone, it's always best to err on the side of caution and use a more formal title.