Well, first of all, I think you should consider renaming your USB drive. I used to name mine "CORRUPTED," but that got some teachers to freak, so I changed it to just 5. A name like NGUSB probably won't get anybody's attention, since it's vague and cryptic.
And if anyone still asks, just tell them that you're backing up some of your important files. Which is kind of what you're doing. An answer like that will probably satisfy that person's curiosity.
You could also do the immature thing and say "your mother."
Boss
well If I didn't like them and they did that I would call them bitch ass hookers and make them go away
SuperMarioBrosS
The problem is I'm in a school environment so that's not likely to happen without getting out of trouble.