SWAG is not to be confused with "swag" which is abbreviated from "swagger". "swag" in this context is used to describe a style, a strut, a brag, a boast, or a vaunt.
Geek 2: Cool! So did you get anything?
Geek 1: Mostly SWAG.
Fan 1: I'm going to a large Star Wars convention this weekend. Want to go?
Fan 2: Sure. Is there going to be SWAG?
Fan 3: Definitely!