Don't mislabel them ... but put something like "goodpbk" ... good pr0n backup, you can even make them longer and more complex. There's only 1 reason to label them non-obviously ... say someone comes to your house and sees a stack of pr0n DVDs ... they're going to think you're some pr0n nut, like what if you get a new gf and she sees all those pr0n DVDs, trust me, most gfs don't like to see that. Of course, you may be lucky and get a nice, tolerant, cool gf who doesn't care or even likes it.
Really most of my HDD space is filled with important backups (20 G), games (15 G), and live cd isos (10 G). Music used to be on there and it took up around 8 G compressed (I use flac, cuz I hate mp3s).