Off the rack in the OR changing room. They will say 'Stolen at the Anytown, KS VA medical center' on them, but where except in the hospital would you want to wear them anyway ? (no, it doesn't help to pick up chicks if you walk into a bar wearing scrubs)
If the hospital you are at doesn't have your small size on the rack, hunt down the OR manager. They will have a stash of XXS somewhere for their often small framed philipina scrub nurses.