You're driving down the road and catch a car (driver or passenger) checkin you out. They will either chase you down, catch you at a stoplight, or drive-by you in a parking lot. They will then flash you their phone number... as if expecting you to remember it and call them. More commonly, the car will be filled with tools or sluts.
Barbie- "OMG! I just got a 'Drive-by Phone Number'!"
Barbie- "Yeah, it was a car filled with douche-bags! Totally not calling that number!"