For this achievement, you have to get caught by slender man with his tentacles. As easy as that sounds there's only one area in the game where you can do this, and that is the area where the forest is on fire in the last chapter of the game 'The Arrival'. When you get to the area where the forest is on fire after exiting the cave, the slender man will start following with his tentacles.
Just simply stand around and wait for him to get you with his tentacles and you should get this achievement.