Hip-hop slang for one's style or behavior. It's pretty much a derivative of the word "style" itself. It is usually in reference to one's general style, including mannerisms, dress, etc. The first usage of this word that I am aware of is Method Man
's verse on "Shadowboxin'
" off of GZA
's Liquid Swords
"Crunch a nigga like a Nestle
you know my steez
burnin to the third degree
sneaky ass alley cat top pedigree"
Incidentally, this sample ("you know my steez") was used by Gang Starr on Moment of Truth for the song (surprise surprise) "You Know My Steez."
I would use this word for describing some dude whose style you don't like. I.E., "man, I don't really feel Russell Simmons' steez. He preaches real hip-hop and all that and then puts out straight commercial wackness." Some of my friends may say, "what's your steez?" By this they are talking about something more local, such as what am I up to or what do I feel like doing. But this may just be my friends and me, I'm not sure. Basically, it's a cool word you can flip to talk about someone's general characteristics.