That was probably written by someone who lives in a colder climate where static electricity in winter can be bothersome. If you have a lot of static electricity built up in you, you can produce a complete, looping circuit through your body and through the horn.
So the keys in the pocket act as a bridge between your body and the bell of the saxophone and the current will then run up your right leg, through the keys to the sax bell, through the horn and back into your body through your mouth. When that happens, it can cause a spark shower from your mpc to your lips which hurts like hell!! :yikes!:
A similar thing happened to a colleague of mine playing at a Shriners' Convention in Dresden last February. It sent the guy screaming to the hospital with third degree burns on his lips. A local news guy caught it on camera.