A combination of ;) and :x, but used mainly by people who are too lazy to hit the shift key. The lips are sealed, and it's winking conspicously, as saying that it will not speak.
<girl 1> seriously, tell me who you have a crush on!!
<girl 2> never! ;x
OR:
<girlfriend> come on! which slut were you cheating on me with?!
<boyfriend> I can't tell you! She's pregnant! ;x