lol Canon is when something is proven to exist within a ...series? Show? Game? It's hard to explain. It's like, if I imagined that the My Little Pony characters use...skiis. It's not Canon until a pony IN THE SHOW actually uses skiis. If a pony DOES use skiis, then they ARE canon. Just like a lot of bronies are speculating whether or not equestria has ever been in a war before because of the guards, the hazmat suits, the air raid sirens, and the fact that Rainbow Dash knew what a tank is. Until some character in some episode mentions a war it ISN'T canon. But since Pinkie Pie came out with a CANNON, a LOT of bronies think this is confermation that that makes the possiblity of a past war MORE possible.





Thus the joke.



...sorry if I confused you further.