To tweak, fluff, primp, improve, make fabulous (most often in wardrobe/fashion context, but others also apply).
Pronunciation: Begins and ends with the same "zh" sound, as in "measure".
Made popular by/notable people you may have heard use it: Carson Kressley of Queer Eye for the Straight Guy, Chef Nigella Lawson, Designer Ralph Lauren.
Origin: Variations used in many countries like France, Russia, Scandinavia, Germany, Australia, Canada.
"Tszuj those sleeves!" as in roll-up and make less stuffy/formal.