Oh, haha. It's a French/English mix: I guess you can catch "I am in", and PLS refers to this : en.wikipedia.org/wiki/Recovery_position. In French, it is called *Position Latérale de Sécurité*, hence PLS. It's a common joke here (in France, maybe it's relevant elsewhere) to say "I am in PLS" when something is "killing" you (not literally, obviously).
Also, my profile picture is a quite known meme : reddit.com/r/facepalm/comments/3y7stx/healthism