Bill saw how cool Jimmy's jacket was so he went out and bought the very same one, and in fact has worn it to outings that he knew Jimmy would attend. It was a swaggajack, plain and simple.
to steal or "jack" one's "swagga" or own unique style or personality that makes them hotter than your boring ass. Often occurs when one is jealous of a much sexier, popular, loved, fun & entertaining individual.
You design an original thing thats all your own & expresses part of who you are. Someone jacks that, claims it is theirs, & looks like a dumbass swagga jacka cause everyone knows it was yours first.
aka: You can jock my shit, but u can't rock my shit.