If you aren't the kind of person who would shoot a rubber band at another person or use rubber bands to power a Lego Arsenal (since you are a loving and caring individual) there are still lots of other wonderful non-traditional uses for rubber bands. The first thing that should spring to mind is creating a Rubber Band Ball. While people can get into the Guinness World Records for things like large balls of twine or barbed wire that isn't anything you'd want to keep around the office. Pee-wee Herman was well known for large ball of aluminum foil, but it got to big to keep in his Playhouse. A Rubber Band Ball is a perfect option for those people who like to have a spherical object made from smaller things that is appropriate to keep in the office.
Thanks to the magic of modern technology you can even purchase a Rubber Band Ball already constructed. Made from approximately 275 rubber bands, it is advertised as fun way to relieve stress by squeezing or bouncing it, but we'll let your imagination decide what you want to do with it. If nothing else it will add a little splash of color to your desk, or the contents of your drawer of pens.
If you are shooting for the stars you'll have your work cut out for you as the current World's Largest Rubber Band Ball is a thing to behold. Something like 700,000 rubber bands were used to create that giant ball of rubber bands so you have a ways to go, and unfortunately you'll notice that most of the rubber bands you'll find around the office won't be able to stretch to a 25 foot circumference. But don't worry, just because we mainly talk Office Supplies doesn't mean we don't can't help you find giant rubber bands.
These giant rubber bands are called "Pallet Bands" as they are commonly used to secure large groups of boxes as they are loaded on pallets and moved around warehouses and onto trucks and such. They are available from with a varying circumference so you can get yourself anywhere from a 72" Rubber Band or a 112" Rubber Band and several sizes in between. Now those are the measurements of the bands before they are stretched, so you'll have some room to grow. Now if you are the kind of person who likes to shoot Rubber Bands I would advise you to not use one of the extra large pallet bands as ammunition. Nothing good would come from it.