This word can be used as a greeting or even to ask for an update on a particular situation. In some cultures, it is simply used as a casual way to begin a chat or conversation with someone.
Defining Wagwan
Wagwan is, by origin, a Jamaican-English expression used to ask "what's up?" or "what's going on?"
Examples
If two pals meet up after not having seen each other for awhile, one of them might greet the other by asking, "Wagwan?" to see what their friend has been doing since the last time they met.
Or, if someone is confused about something they see or hear happening, they might ask someone, "Wagwan with that?"
So ... what exactly are you saying, teacher?
Wagwan is basically a slang term or expression that is used to greet a friend, to ask for an explanation about something, or simply to ask, "what's going on?"