AMD 5 Kevin

I so unoriginally decided to read the wiki article. I'm only curious as to how this all happened, I understand how slang comes up but how do people violate their grammar for a different countries? Its very early for me some I cant think of anything for English that would even be equivalent. And I'm even more confused how the 's made it to Germany since that's not even a slang term or something of the sort it is literally English grammar. I barely know English grammar let alone would i try writing English with German grammar.