If you have a U-lock on your bicycle, there’s a good chance it’s made by Kryptonite. You may also have heard that people can unlock your U-lock with a Bic pen. This turns out to be true (here’s proof).
Kryptonite has acknowledged the problem, and is asking people to fill out this form to exchange their lock for one that can’t be 0wned by a pen. You’ll need your lock, and its key, when you fill out the form.