Erm, well, straight off the bat: question 1, "Do they have the 4th of July in Canada?"

That's not common sense, thats just knowledge, and not really common knowledge if you have lived in the UK all your life. I assume the 4th of July is some sort of American event, a holiday or rememberance day. Also, we all have a 4th of July. xD I'd like to see a Britland quiz.

"After you shave, does the hair grows back thicker?" - this is just science; a myth that is either proven to be true or not, ... I have no idea if it was, because I've never looked into it. I guess Mythbusters is aimed at people lacking in common sense. Oh wait, I'm thinking of longer... now I get it... I may have common sense, but I'm blonde as hell. lol

I'm apparently not very bright according to this quiz. lol