As an adjective, jyne is a slang term for anything fresh, cool, hip, awesome, or enjoyable. Anything with a good connotation can be considered as "jyne". Someone can be "jynin', and really cool people can be considered as "jyne-stas" if they have a lot of swag or you can feel the jyne vibes radiating off of them. Jyne can be used as a verb to describe hanging around in replace of words like "chillin". Pronunciation rhymes with: wine, mine, fine, shine, etc.
Nicole: Have you guys heard that new song by Sean Paul?
Me: "We Be Jynin"?
Nicole: Yeah that song is freakin' jyne, man.
Me: Yeah, I was jynin' with some jynestas last night when I heard it.
Boy: hey wassup?
Girl: jj, u?
Girl: ya, just jynin!