A Christmas time gathering of lacrosse fanatics during which time the participants exchange gifts with another laxrat. Essentially a lacrosse themed Secret Santa.
"Yo, what'd you get him for laxmas?"
In the Spring time, as the snow melts, Santa brings the bros some lax twigs
Bro: I can't wait for christmas!
Dude: Yo Laxmas is more ill.
Brah: Yeah Laxmas is dank.