When I was in the military, part of my job was assembling jet engines. We had these service carts with molded plastic trays on them. Every single part on the engine had a slot on the cart, so you always knew that you accounted for everything.
Every now and then, we would mess with the Quality Assurance guys when they came to sign off the job. Upon completion of an engine assembly, we'd gather up a few screws and nuts and stuff from around the shop, stick them in a Zip-Loc bag, label the bag "Miscellaneous Parts", and throw it on the service cart.
They look on the QA guy's face was priceless!