A phrase used back in the days by German Minecraft Survival Games players. They often used it when they wrecked some noobs who had a larger ping than themself
Stands for "Learn To Play." It is shorthand used in gaming and has spilled over into internet chat rooms and forums. Any noun can follow "l2play" in order to insult the one being spoken to, e.g. "L2Play Politics" in order to insult presidential candidates.