Unstick a zipper with pencil lead
Although they are a marvelous invention, zippers can be finicky. After some years of wear, or if it was never of good quality to begin with, you might need to start being careful when you zip up and down since they can get stuck. If you ever get annoyed by a zipper that will not budge, then we have a possible solution.
Grab a pencil and rub some of the lead near the place it has stopped. The lead can act as a lubricant and get it rolling around smoothly again. Move it back and forth to make sure the graphite spreads to all the corners that might be a bit rusty. Hopefully, it will not get stuck again.