One that acts 'silly', 'foolish', and 'stupidly'. Additionally, it is a more offensive way of calling someone that acts likes a 'dork'. Similarly, dorksters are a group of dorks and hang out in groups.
A conservation between person A and person B:
Person A: Lol, that person has been acting very lame and dorky!!
Person B: Congrats to him, he is officially a dorkster.