PUBG What "Lean" THING?

So I was leaning and shooting a guy on the other side of a window, and he says I am using the lean thing to win... What lean thing???
For future, it is called peeking, and if you would like to set it like i had it, go to settings, game play, and change peek from hold to toggle - it frees up your peeking finger (for no specific reason, other than I hate holding down the peek buttons while shooting).