A Pointless Tattoo. Normally worn on the upper arm or accross the shoulders. The male version of a 'tramp stamp'. Usually tribal markings. Great if you are from a Polynesian Island but pointless if you if live in the suburbs.
Michael worked in a factory by day but a night he liked to wear a sleeveless shirt to show off his twat tatts. Then every one would know he still a free spirit at heart and may be a little bit hard as well.