It is used by people who arn't sure on how to start a convo so will say "sup" instead. It is also an abbreviation of the phrase "what's up?". When someone says "sup" it is often a retorical question and is followed by either no answer at all or a stupid answer such as "the sky".
*Dude101 enters the room*
Dude101: Sup people?
jake: sup man?
bob: not alot.
A term that cool people use because they are too damn lazy to say What's up. (Too much effort involved there man.)
A contraction of the phrase "what's up?"
Jack: Hey, sup?
Jill: Not much
A greeting, an abbreviation of "What's Up"
Yo my brother, sup! Nothing you?
How everyone starts an IM convo after saying hey. It is then always followed by "nm"
sn2: nm u?
The "point" to a "sup" is one trying to say hello, sup was derived from wassup, which is another variation of What's up. What's up isnt an inquiry but an informal way of saying hello, although it can at times be answered with an actual response (Ex 1.)
Many do in fact actually respond to the question with an answer but quickly disregard it and fray away from it... another way of responding to it would be (Ex 2.)
Ex 1.) "Sup matt?", "Nothing much just watching gay porn on my computer"
Ex 2.) "Sup jew?", "Hey man, havent seen your ass in a long time... wanna hang out on Saturday?"