Yass is a loose confediration of imbred family fucking each others and wanking over japanese people
This word can be used to speed up an insult that is thrown into a conversation or just to be flat out flaming!
Also, this word is a combination of the words "you are an" and "ass". See the connection...
you are an + ass = y'ass
Jon: "Y'ass, Erika is my one and only true love so back off!"