Cannae was a city in the Roman Empire, notable for the Battle of Cannae, in which the Persian general Hannibal brought a force of 60 elephants and 3000 or more men across the Alps to attack. His objective was weakening of Roman militia, in which he succeeded.
Cannae is also a military battle archetype, commonly called a "Battle of Annihilation", meaning a battle used to weaken enemy forces significantly.
It is also a mispronunciation of "Can't" in Ireland and similar locations.
Scottish means of saying "I can't be bothered". Commonly said when something goes wrong or when you just can't face doing something, or just as a standalone phrase. Bothered is pronounced " bo urt".