Definition of Tart card

Tart cards are cards found in phone booths in London (especially) and in certain places elsewhere in the United Kingdom that advertise the services of call girls. They are typically placed in phone booths by professional "carders", who tour the phone booths, replacing cards which have been removed by the telephone companies' cleaners. Placing them in phone booths is now illegal. Similar cards may be found in phone booths and scattered on the streets of Las Vegas, where they are known as "sex cards".