This is not really a prank as much as a great way to entertain yourself and build camaraderie or notoriety in a company.
Many years ago, I used to work for a company that operated a fleet of fishing vessels and shore processing plants in Alaska. My job was to ship packages and parts to the various offices. These packages could range in size from a manila envelope to a large shipping crate.
The company office was always serious and dour which was a shame, but on occasion I would find an opportunity to have as little fun with the packages. Sometimes it was bags of candy or wacky notes or comic drawings. Sometimes it was something more serious and fun like a magazine. Sometimes we would get something back, but usually that dour attitude of the company permiated every corner of the empire, so we never got much in return. Well, it was that and the fact that there isn't many funny things to send from a shore processing facility except for maybe smelly fish guts.
Although this is not really much of a prank, it can lead to some very fun exchanges and certainly sends goodwill to your other coworkers you may never meet. So if you happen to ship packages to the same people in other offices with some frequency, consider adding a few fun things to make the day of the co-worker at the other end. You can always send candy, stickers, magazine, funny comics, maybe even a printed page of a prank from this Web site for them to pull on an uptight coworker. Items like these don't add much to the weight of the package, but will help make the day of your remote co-worker far more tolerable.
If you find someone that appreciates your gesture, try to step up the fun by sending them small toys, weird curios or other items. Remember, their job sucks just as much as your job, you might as well band together and enjoy it.