LUKE: Geez! Don’t sneak up on me like that.
LORELAI: Yeah boy, I was lucky you had your phasers on stun, huh?
Phasers are the standard weapon (and tool) of choice in the Star Trek universe, apparently giving off some kind of “beam” of pulsed energy. They can be set to stun, rather than kill, so that an opponent or threat is simply shocked, rather than vaporised.