To be creeping around, searching, surveying in a low down manner. Like a predator in a murky swamp.
Dude 1: This club is gangster. Where did DeShawn go?
Dude 2: He is murkin' for drunk girls on the dance floor!
to beat someone with your awesome skills, to be awesome, to do extremely well on something
Dude 1: "Wow, you're really murkin' in this track meet"
Dude 2: "Thanks bro, i know."