That's actually a backronym, or an acronym back-formed from a word that already exists. In other words, that's not real. It was made up to insult people who use the word "swag." A noble effort, but misguided and homophobic.
On UrbanDictionary, swag is most accurately and classically defined as "The way in which you carry yourself. Swag is made up of your overall confidence, style, and demeanor."
However, swag is largely overused as a stupid saying that kids use to try and make themselves sound cool. It doesn't work, and the term has become so overused that in the popular culture it doesn't really mean anything anymore when people say it. It's just a noise.