Enter the realm of the forbidden, as this mesmerizing hit series from the National Geographic Channel pulls back the curtain on the world's most exotic cultural taboos. This revealing episode of Taboo explores the ancient, often controversial custom of tattooing. From marking someone as friend or foe, to signaling social rank, to body-covering displays of self expression, the intricate art of the tattoo is one taboo with an age-old appeal that's more than skin deep.