i think I can beat all these stories. I recently got a 3+ kg parcel from China, a large cardboard box, which had a steel plate(!) attached to one end of the box wrapped in white paper and all stickytaped together as part of the box. I would have missed it if the empty box wasn't so heavy!
We can only guess, either they bumped the weight up to get in the next shipping bracket to save money, or they bumped the weight up just so they could charge me a lot more...