Originally used to describe a guy who walks, or saunders, around in such a way, looking like every girl on the planet wants in his pants. These guys traditionally wear Hollister or A&E shirts, pre-frayed jeans, and/or "popped" collar polos.
The more "modern" usage is synonymous with "douchebag".
"Uh oh guys. Look what's coming."
(Guy in abercrombie shirt walks by, "strutting his stuff")