Hi Karmen:
I've worn battle dress, bush dress, combat clothing (combat), work dress, service dress (sometimes incorrectly called DEU), environmental dress, mess kit , tropical tans, tropical worsted ("TWs") and many others in my 35 years (counting four years of cadets). I grew up in a military household posted all over Canada and Europe and I never heard Canadian soldiers call their uniforms "fatigues"... it is another US expression creeping into our lexicon, much like "tour of duty".
As a young cadet and soldier, everytime I got into minor sh*t, I received extra work and drill, "jankers", confinement to barracks (CB) and extra duties (as a young officer) but I don't ever remember being 'sentenced' to fatigues. I have sentenced soldiers to extra work and drill, to CB and to stoppage of leave and I have given rambunctious young officers extra duties (as orderly officer) but I have never sentenced anyone to fatigues.
Different regiments and corps had slang of their own which is why Jon and I may have different experiences but I'm pretty certain that fatigues is also an American term that slid in to the lexicon, perhaps in the 1940's.
I have a friend in NDHQ who is probably the Canadian Forces greatest expert on terminology, official and unofficial (read slang)... I'll ask her.
Mike