Simply meaning "yes" or "yay". This word is used at any occasion and at any time and place.
The word was mentioned on many Vines, and is being used by many Viners to imitate a "white girl". Some people use the word "yass" to create more of a "Starbucks, Chipotle, White girl".

Scottish way of saying Yes ( in celebration)

another word that is similar is Yaldi

"yass" is the most annoying way of saying yes. it doesn't stand for anything, but if you ever see somebody saying yass, just tell them this:

a word that is only commonly used by flamboyant males or minion loving females

A term that only fucking stupid people use. Like Rachel's , Britney's , Jaclyn's , Duffy's and etc.

Bin him mum by ym in un

Yass - Internet slang for yes, a celebratory slang