I believe you are thinking of a much earlier event in the second dungeon, where you can crawl through a hole in the wall without getting stuck if you have a small ass, but get stuck if you have a big one. This event has always just been "You get stuck." There's just different flavor text for if your curves get you stuck, or if the building itself conspires to get you stuck. There is a hidden hallway which is only hinted at by a character walking through the false wall into it, and within that hidden hallway there are faint footsteps which hint at a hidden entrance to the same room, without having to get stucked and fucked.