Allow me to set up the whole situation.
So you share office space with the UNIF crowd, leave without eating your chips, and you think that’s safe? Think again.
Step one: Open the bag from the bottom and “EAT DEM CHIPS!”
Step Two: Cut up some cardboard, chip shape style
Step Three: Fill the bag, semi full chip factory rip off style. They settled in transit, pffft
Step Four: Double side sticky tape that bag
Step Five: (A crucial one) Take a can of compressed air and insert into the bag. Seal the bag all the way to the straw. Make sure you seal it nice to trap the air. Overfill slightly, remove straw, and close the bag.
Step 6: Place back on the victims desk same as was, sit back, wait until tomorrow, and bask in the prankish glory of surprise.
And the reaction. Sorry Harold.