from the wiki grab-bag:

Swag is actually an acronym for "Stuff We All Get", originated from the .com years where companies used these give-away items as promotional mechanisms.

Swag can also stand for "Stolen While At Gig"


hmmmm. not a wiki classic, I fear. This marketing device long predates the dot com bubble. It might be fairer to describe these as post-facto rationalisations (or folk etymology) unless they have decisive citations, since the natural meaning is long established and is a more natural leap (swag as booty, loot).

http://www.bartleby.com/61/97/S0929700.html