[He doesn't mind - not like she can hurt it much by poking it]

It's... a computer term - a type of music file. [It's either say that or try and explain all of computer science ever (most of which he doesn't know himself) to the girl.]

You use a computer to put the files on that, and then that takes the files and makes them into music. Don't ask me how all the programming and stuff works though, I have no idea.