Let's put this to rest once and for all. The way in which Canadians say "about" comes from our British ancestors, and it's actually way closer to "aboat" than "aboot." According to an interview with linguist Charles Boberg in the Ottawa Citizen, this sound is known as "Canadian raising," and happens when the "ou" comes before sounds that have no vocal cord vibration (or "voiceless" sounds), like "t" in out.