Everyone has had this mishap at some point in their lives. You move a certain way and that tiny hook and eye pops off. Solution: A bold skirt and pants hook!
This is what it looks like. You usually need only one to close a skirt or a pair of pants with a normal sized waistband--two for an oversized waistband. These should be sewed on with a double thread, hiding the knots if possible. I always try to hand stitch these and catch the internal seam allowance for stability.