Hunky, studly; like a high school football player. Looking like Mark Wahlberg in the era of his Calvin Klein ads. Sometimes it also implies someone that is not too bright (as in the case of most jocks). Usually used to describe someone younger, really fit older guys are, well, just really fit older guys.
“Shelly, did you see that guy at the other end of the dance floor? Ohmygod, he is so totally marky mark. I’d like to feel HIS vibration.”