When a second person (who usually is a kid or a whimp) says when someone seems to have more of a mental & physical power over you. They tell you to leave because of a particular problem.
Don: "you don't pick on my younger brother, GET OUT OF HERE!"
This is how Toronto mans version of "oh yeah?". Can also be used with the same sarcastic undertone as "oh yeah?" too.
Mostly just a "yeah" but of course followed by the traditional Canadian trademark "eh". Drizzy says it too.
Adam: Yo, G, mans are 'bout to catch a straight defaz
Greg *looks sassily to the boys* : Yeah eh???