My first introduction to Canadian English being slightly different than American was a physics professor my sophomore year who in the first lecture kept saying zed. I thought it was a tic.

Later I moved to Germany, I finally figured out that zed was a Commonwealth English thing from my Canadian coworkers. None of my German coworkers could understand me when I said zee, because it sounds like "c", I guess. So I'd say tset (the German zed equivalent).