Here in Pennsylvania, as in most other high-population USA states, we have license plates consisting of seven characters: in our case, three letters, a hyphen, and four numbers.
I have on occasion seen plates that begin with KHG-, the German-language abbreviation for keuschheitsguertel.
I have also seen KTB- plates. KTB is the abbreviation for Kali’s Teeth Bracelet, a rather severe male chastity device.