1) a question when one is curious about what is going on around him.
2)A popular greeting greating used instead of "hello".
3) A state of confusion when used in a situation where both definitions intertwine.
eg. when you have just met someone whom you know and who may be curious about a situation or the goings on around you.
Taken from the word happening. Can be used as a greeting, an exclamation of enjoyment, a form of asking the well-being of another person and a way of saying that everything is well.