I learned something creepy about printers today. It turns out, most major printers add pale yellow dots to every page, which encode the date and time of the printout, as well as a serial number tying the paper to a specific printer.
It's called "Printer steganography." According to Wikipedia, Steganography is "[T]he art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message[.]"
Now that I'm aware of this, I'm having trouble thinking of anywhere I could print out a document without making it obvious where I am. I can't do it at home, because duh; I can't do it in the newsroom at school because I'm one of like 10 people who can get in, and they[1. "They" being any powerful or well-connected person or group that either has something against me or makes any kind of mistake that leads them to believe they have something against me. Or someone less well-connected, but with a serious vendetta against me and access to, for example, the above-linked EFF site where the Xerox printer dots are decoded.] could compare the time on the stamp to the times that computers were in use; I can't use the computer lab at school because they make everyone sign in... I can't remember how the computers work in the library, but I do know I have to pay for copies. Maybe they don't log people's names.
Not saying I have anything particularly sensitive to print out, and as far as I know nobody hates me enough to track me down by stealing pieces of paper I might have printed, but the whole idea totally creeps me out, anyway.