Internet-speak for "picture". Usually used by those who are perfectly capable of interacting with intelligent speech over the internet, but occasionally use net-speak sarcastically (see lawl, roffle) to mock the people who are not capable of communicating intelligently online. This type of net-speak is frequently used with SARCAPS.
Person 1: "I posted a piktar up on the forums."
Person 2: "O RLY? I'll go check it out in a little bit."
Person 1: "YA RLY. I KNO U WNAT 2 C MY HAWT PIKTAR LAWL!!!11!1one"
Person 2: "HAY R U HAWT IN RL?!??!?! Hehehe."