If you are a threat to national security and use only emojis to plan your upcoming attack on the homeland, you’re on the safe side.
Odds are that the National Security Agency (NSA) and Britain’s Government Communications Headquarters (GCHQ) spy agency are less likely to find you if you stick to smiley faces. PRISM and other mass surveillance systems are not equipped to store emojis in a way that won’t translate them into black, undeciphered squares, similar to those you get when receiving an emoticon on a Blackberry or any other kind of dumb phone.
It’s almost certain that these agencies employ thousands of people who can understand needle-emoji, bomb-emoji, pistol-emoji, or any other ticking bomb-plus-clock-emoji-type messages, but the complex algorithms they use for automatic threat detection simply can’t cope with the full extent of the Unicode standard and the legacy-encoded emojis.
For the rest of the story: http://www.dailydot.com/lol/emoji-emails-nsa-privacy/