Short for Diesel. This word is used as a universal adjective for anything of greatness. Also spelled dies.
"Ya know whats diez? That home run he just hit"
" DUDE!!! that party was DIEEEEEZ!!!
" This class is gunna be so diez cuz the teacher doesn't care about anything and no one is gunna try. YEEEEE"
"That kids a faggot.... he is not diez.... hes a fucking tricycle"