KGB Disappearing Ink Pen

KGB Disappearing Ink Pen

Sorry for all the thinkgeek stuff, it's just...well.....I check them everyday ok?! Anyway, the KGB Disappearing Ink Pen is not your ordinary dime-store gag. Developed by KGB scientists, anything you write with this pen will completely 'self-destruct' (ok, disappear) within 48 hours. There'll be no trace of your message, even using UV lights or other detection methods. I'm trying to think what to use this for. Prank messages for which I can't be blamed? Lending a pen for vigorous note taking only to see their work vanish? $14.99. Use responsibly... But of course I'd love to hear your ideas in the comments.