The 'unspoken eh?' occurs when speaking to a Canadian trying to pass for someone who is not Canadian. Canadians often say "eh?" at the end of a sentence, when trying to pass as someone not Canadian, they will try not to say, "eh?" but the person the Canadian is talking to will notice something is wrong with what they said and hear the 'unspoken eh?'.
Canadian Guy: Hey sexy. Wanna go out, e- err, uh, yeah?
American Girl: OH MY GOD! No! You're Canadian!
Canadian Guy: Damn! This has happened to me 5 times today! How could you tell, eh?