The continental United States is only four time zones wide, so most Americans can do the math very readily. For sake of simplicity, they just ignore Alaska and Hawaii. Canada is much wider, though, involving six times zones. To make things even goofier, in Newfoundland, they are 30 minutes off the rest of the country. So, for example, when it is 5:00 a.m. here, it is 6:00 a.m. in Nova Scotia, but it is either 5:30 or 6:30 in Newfoundland (i've never figured out if they are slower than the time zone to the east, or the one to the west).
They just do it piss everyone off, because Canajuns make jokes about Newfies.