On Tonga all men were tattooed from their lower thighs to just above their hips. Because they appeared to be wearing short trousers, this decoration is known as the ‘trouser tattoo’. The trouser tattoo was also common to all men on the Horn Islands, north of Tonga, but they too were not noted by the seafarer Jacob Le Maire either, who had reached them two centuries earlier.

The inhabitants of Tonga and the Horn Islands probably adopted the style from nearby Samoa. In Cook's time, many young Tongans made their way to Samoa, apparently the home of the specialists, to be tattooed. The trouser tattoos of the two island groups shared many similarities. On Tonga, they consisted of narrow bands encircling the body and sprouting neatly arranged lozenges, triangles and parallelograms. The only exception was the Tongan king, who was distinguished by the complete absence of tattoos. The Tongans told members of Cook’s expedition that the trouser tattoo provided magical protection during battle to the warriors, who only wore loincloths.