A friend just sent me this. USB drives use Flash memory, which means the the ones and zeros of your data are stored on transistors. When you save data, a binary zero is set by charging the float gate of the transistor, and a binary one is set by removing the charge. To charge it, we add electrons, and the mass of each electron is 0.00000000000000000000000000091 grams. This means that an empty USB drive (which mostly holds zeros) weighs more than a full USB drive (which has ones and zeros).
That sounded so cool I had to Google it! The first discussion I came across seemed to debunk the idea, because if electrons were added the device would have an overall charge, and it doesn't... However it does weight a teeny weeny tiny bit more because it is in a higher overall energy state so it still qualifies as an "interesting fact!. https://www.quora.com/What-weighs-m...ow-does-it-affect-the-weight-of-a-flash-drive