A New Hampshire mom got tired of telling her four kids to go to the bathroom before they got in the car, so she put the message on her license plate: “PB4WEGO.”

The mom, Wendy Auger, said the plate elicited nothing but laughs and appreciative honks from other drivers for the past 15 years. But last month, she received a concerned letter from the state’s Division of Motor Vehicles. The license plate would have to go, the department said, because it was associated with “sexual or excretory acts or functions.”