i wish i could take credit for figuring this out (the youtube video that gave me the idea was taken off the site, but look for light painting on youtube, there's plenty)

how are you doing that?

dude..how the FUCK do you do that?

pretty much. i had a friend hold the shutter open while i moved a light pointed at the camera

Put in more technical terms, long-exposure photography. >_>
Lots of SLR cameras have shutter times of up to 30 seconds or so. With practice, and increasing the ISO so the sensor reacts slower and doesn't draw so much background light, you can play around and get a very clear photo from a tripod and draw in the picture with a laser pointer.
Same sort of thing is done with taking pictures of Fire Spinning, Fire Poi et all. Had quite a lot of fun with it myself - Sparklers look amazing in long-exposure photography.

*shameless plug*
http://wdwescott.deviantart.com/art.....-Wave-41324599

That's a set of LED Poi with the same kind of long-exposure settings. Looks very shiny when done well!