The loaded shotgun. No need for a mag.
Pump the action once, fire.
Or, just in case, grab the USP. Point, pull trigger (DA).
Or, with the other shotgun, pull the bolt, point, shoot.
Or, with the P2000SK, Point, pull the trigger (DA).
Or, ....well, you get the idea.
But, realistically, whatever is at hand to fight my way to a "proper" weapon.
Now, do keep in mind I live alone and have few visitors (I think one in the past 5 months). So for all of you about to whine about my safeties not being on: