How do I glitch Phasewalk?

I've seen players who act like they're in Phasewalk (e.g., sparking with Brilliance, moving very fast, Phasewalk background sound), but they are carrying a weapon. Other effects include being completely visible and able to shoot and throw grenades. Further evidence that leads me to believe that this is a Phasewalk matter is because after a normal Phasewalk length of time, they come out of it with the characteristic, ending AoE. Is this just a glitch for me or are they doing something special?

In Borderlands, there is a class called the Siren (A.K.A. Lilith). Each of the classes has a unique Action Skill. Hers is called "Phasewalk" (PW).