The .nfo file included with a pirated software package. Those in the know will open this with MS Notepad, as it is actually a plain text file. The nfo usually contains a pirate "crew"'s ascii art logo at the top, which bears a resemblance to raw code to the uninitiated, and gets mangled into gibberish if opened in anything other than Notepad.
Usually associated with: ISO, crew, rar, crack, keygen, rip, reg, courier, 0-day.
Q: "I opened the rar from the 0-day. Many thanks to the courier & crew for this one; glad it's not a big ISO. But where's the serial number? Or do I have to use a keygen to reg this rip?"
A: "Just open up the nfo, newbie. The cereal is in there."