1. The act of scraping the sharper point of a car key across the windshield or front door of a car, making a screeching sound and leaving a large scratch in the paint. Often preformed in anger or spite; a form of vandalism.
There is one other, not-so-well-known meaning:
2. The act of saying the phrase, "I need the car keys" and plunging ones hand into the front pocket of someone elses pants or hoodie to retrieve said car keys. This is usually down to a boyfriend (or husband) via the girlfriend (or wife). A big turn on, and surprising if they didn't expect it.
2. "I need the car keys baby." (followed by the fishing around in someone elses pocket and then they are found.) "Thanks."