It can mean anything from chillin to partying hard. Whatever it is, it's definitely spreading good vibes and having good times.
"Yo bro, what you doing today?"
"Laxn."
"Drizzy was laxn at the crib today."
The acne that occurs around the edges of the face soon after wearing lacrosse helmets (or football etc.)
Jim: Bro, you should probably get some proactiv.
Dave: I know, my laxne's been terrible ever since the second week of the season.