It's a very informal way to greet someone and is usually used among friends or people who are close.
Here are some other ways "ssup" can be used:
* "Sup?" - A shorter, even more casual version of "ssup."
* "Ssup dawg?" - A playful greeting often used between close friends.
* "Ssup, bro?" - Another playful greeting typically used between male friends.
It's important to note that "ssup" is a very informal greeting and should not be used in formal situations.