Why we do it.....Girls just wanna have fun yo!
I personally love the idea of bringing some minutes of random maddness to the unsuspecting public and then leaving without a trace...hopefully to the confusion and amusement of others.
Oh yeah and it's a cheap way of entertaining myself.
The "other" (and by other we mean pranks and the like) include:
Projecting images onto buildings in the C.B.D and other interesting locations..
Phantom Nightclub (aka the door cue that never moves for the club you never new existed)
and more.....