Term used to describe someone who is married. I first learned this when I was in college having a conversation with my friend Lindsay.

Lindsay: So Sam kissed me last night.
Me: Your boss Sam?
Lindsay: Yeah.
Me: Do you like him?
Lindsay: Yeah, kind of.
Me: But he's your boss...
Lindsay: Yeah, plus he has left hand disease.
Me: What?
Lindsay: You know... left hand disease (pointing to ring finger of left hand).
Me: Ohhh! Yeah... you probably shouldn't go there.
Lindsay: Yeah.. probably not.