The word used as a replacement for when the speaker cannot recall the defined name of said subject or activity. It is also used as a way to add variety or mystery to the conversation.
Hey what's up?
Nothing. Just finishing up on some stuff I have been working on.
Nice.
Things and junk, but sometimes you just gotta stuff your face with donuts, and the stuff the donuts with a donut hole which you later stuff into your face as well.
I like this. I was watching a video of some music. I thought that was 'Stuff'. Stuff means that it is really good. It has lot's of great interest in it!
Tonight I was watching a newvideo of Carl Cox. That was stuff!