What is You Can Never Win Against A Smiling Man?
1.
A stance one takes in an argument to smile, remain calm, collected and to focus on the argument's topic at hand without referring to falling back on snide remarks or insults of the opposing side.
During an argument, you sit back with a smile, keeping your cool and staying confident, picking your words carefully, even admitting defeat at certain points if the other is right.
Most of the time, the opposition will be backed into a corner after being at a loss for words for you being completely correct and unless they are a competitive person who refuses to admit defeat or that they are wrong (which most people are), then they will resort to other means of winning the argument, in which case they have lost regardless.