There is nothing wrong with slang, in speech. The more of it you learn, the more you will be comfortable speaking English. It is way better to know this term than to wonder what it means.
I think the point is that you should recognize what is slang, and of the slang, what is inappropriate in "mixed company" (I mean, what you should not say in front of my mother). There is nothing inappropriate with "way" in any sense discussed here; my point is that it is "inelegant" - not wrong.
As "2006" pointed out, it's "in the dictionary" (as are a lot of downright vulgar terms), with an accepted usage defined. It is not wrong. And it won't offend my mother, either.
Go! 'Way with you! Enjoy this rich language! It's way too good not to!