Why do all Canadians sound so weird?

U.S. commentators (see South Park) have drawn attention to the stereotypical Canadian pronunciation of about. To American ears, the Canadian pronunciation of about often sounds like aboot, but this is only an illusion. Canadians actually pronounce the word more like “a boat”.

This confusion is created because the more familiar pronunciation of /aw/ is articulated with the tongue in a low position, and because it raises to a mid position in Canadian English, speakers of other varieties of English will immediately detect the vowel raising.

The problem is that listeners will think that the vowel has raised farther than it actually does, all the way to /u/, which is a high vowel—hence the mishearing and not-quite-right imitation.  This phenomenon is known in linguistics as Canadian raising, and is not restricted to just Canada, as many Northern U.S. dialects have clear raising as well.