I know that these two expression, in certain circumstances, have no meaning and are optional. I'm trying to figure out how to use them, even though they have no meaning.
This has a meaning, (negation):
On the other hand, this use of 什么 means nothing:
This has a meaning (forgetting something you should remember):
This use of 来着 has no meaning:
Just to clarify, I understand the situations where these expressions have a defined meaning. I just can't get my head around the usage when the expression is optional. I can leave it out, and I'm content with that. But for some reason my teacher in Beijing felt the need to show this to me, maybe to make me sound less 'academic' when I talk?