I read on various places, that 'no is a complete sentence'.
For example, such-and-such has invited me somewhere that I don't want to go, how do I say no?
And then there will be a bunch of replies to say 'no is a complete sentence'. Which is fine, if you are actively trying to break up a friendship/relationship, but don't then complain about how few friends you have.
Basically it's bad advice in many cases, in my opinion.