Sometimes the instruction "Don't try this at home" just seems like an invitation. What's the worst that could happen, aside from burning your house or office to the ground?
In the latest video from The Royal Institution, Andy Marmery shows how water cooler bottles can be made into bottle rockets. It starts with slow-motion footage of how fuel burns inside the bottle (beautiful science, to be sure), then—no spoiler, I suppose—it's time to turn these bottles into rockets.
So while I really do urge you not to try this at home, I can think of no better use for an office lunch break. (And the office isn't home, right?) Enjoy: