0 used to ask someone what the problem is:
What's up - why does everyone look so serious?
What's up with Terry?
What's up, bro? How are you doing?
1 infml used for asking how someone is or what someone has been doing:
"Hi, Chuck, what’s up?" "Nothing much."
NYA ORD
European
May 10, 2021
DAGENS ORD
Shimmer
what's up?