First, you pick what you like. In this case, a water... (reaches in through the hole in the glass to tap the tag beneath the water.) There's a letter and a number. A5. Notice there's a pad on the right side, with letters and numbers corresponding to the appropriate item...?

(slowly nods at him before continuing.)

You tap one of your dog-tags here on this sensor, your dog-tags are holding all of your money wirelessly so you're gonna wanna keep it with you. Like they said, unfortunately. (tapping her dog-tag, but the thing's too busted to read it... oh well.) It'll take the cost of the water outta your account like that, you type in the selection number, then you watch the machine drop it for ya.

(points to the rungs that hold the items, then down to the drop-box below, pushing the twisted metal flap with a creak.)

Finally, you grab your shit and go. Easy, no pain strategy to buy from vending machines, just like that. No need to pillage the poor things.