When one takes his shoelaces and wraps them around his balls and works his way up criss crossing his shaft in a Roman Sandal fashion ending with a bow knot. Thus giving you the Roman Sandal.
This was originally slang used by soldiers in the British Army. It probably dates from the 1920s and was in widespread use during World WarII. 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.
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.