Rubycon's suggestion. Keep a propane torch in your drawer at work. You can also cook a nice steak for lunch.
Another thought: Do you have access to a large can, metal box, or something similar? Go outside (preferably), and find some rocks to prop the can/box on, so that the bottom is off the ground. Toss some wadded scrap papers underneath and ignite. Keep feeding more paper as necessary while your poptart grills on top. You can also cook a steak this way. Just tell the boss that you read that MIT had written an algorithm where they were able to scan in shredded paper and reassemble the original documents electronically. You were just making really sure that no one was going to find out what was on those documents that needed to be destroyed.