MI6 “used bodily fluids as invisible ink”

Not sure if this qualifies as “ick” or “cool”:

http://www.telegraph.co.uk/news/uknews/8015180/MI6-used-bodily-fluids-as-invisible-ink.html

Article doesn't say if you hold the stuff over a light bulb to make it readable, though.

Update:

• Why does this seem like it should be from a Warren Ellis comic book?
• Is this the first new euphemism for masturbation in years?  “Making up some invisible ink.”