Buy Bouncing Bettys once power is turned on and make sure you have enough to buy 1 of the perks and then a gun from the random gun box.

Once it is on, go up to the perk machine and wait until you can see the hold X to buy, then get your Bouncing Bettys out.

Plant the first 1 in front of it, then as soon as you plant the second one hold X to buy the perk.

This will leave you with the perk and no gun.

Run to the random gun box, buy a gun and once you have it you will have three guns.

This glitch can be used more then once.