I am only guessing, but Canadians (on average) tend to tip lower than Americans. I have always considered 10-15% standard. In the U.S., they tell me that it is

I am only guessing, but Canadians (on average) tend to tip lower than Americans. I have always considered 10-15% standard. In the U.S., they tell me that it is 18-20%. I could never bring myself to tip that much when I lived there. There may be a core of truth to Canadians appearing cheap to American waiters which may be where the euphemism started.