This was originally slang used by soldiers in the
British Army. It probably dates from the 1920s and was in widespread use during
World War II. A sand rat is a whore, hooker or
prostitute in a seaside town. These women were not based in a bordello but walked a pavement ‘beat’ (see also pavement fairy) and were known as sand rats because, like rats, they only came out at night and would take their clients down to the beach for sex on the sand.
A British squaddie
going on leave would be asked by his mates what he
intended doing. His itinerary would almost certainly include the phrase ‘sand ratting’. This meant that he
intended to engage the services of a sand rat.