Chicken lights are a subset of cab lights used on trucks. While the nickname "chicken lights" may seem off-putting at first, the reason behind this moniker is not. In the early 20th century, truck drivers installed lamps on their cabs as a warning against the widespread problem of chicken thievery. They've started using the lights to demonstrate their presence at night and discourage would-be thieves. Nowadays, many drivers often employ "chicken lights" in addition to their regular headlamps for additional brightness. These lights are not prohibited by law but may confuse oncoming traffic. The lights not only increase visibility but also save electricity and serve a long time. Chicken lights are even mandatory under the law in several jurisdictions.