I used to keep a rather large pocket knife clipped to the lighter pocket in my jeans. I accidentally took it through security a few times. Once when I was on the plane I was looking at it thinking, “Holy shit, how is this possible?” I looked it up and it turns out the scanners actually have a hard time seeing objects on your hip because of the way they scan. They are good at seeing objects in front of you or behind you, but an object perfectly aligned with the plane of your hips will often be missed.