Punctuation of first sentence

"Hello there, Koh Yoong Liat!"
Or you could say "Whatsup, Koh!"
(Just kidding)
(...but you could)

In the interest of understanding-
I just read the definition of "What's up?" True, it can be used as a confrontational phrase meaning "What's wrong with you?" or "What's your problem?". But it is also a slang friendly greeting that means "What's going on in your life?", "How are you doing?", etc.

Hello there, Koh Yoong Liat!