1 Tattoos and doctors do mix. Tattoos are used for medical purposes like radiation therapy and reconstructive surgery. In the former, tattoos are used to mark the outer limit of a treatment area so that radiation can be delivered accurately and consistently to the same spot. And in the latter, tattooing is used to help create a normal-looking nipple and areola for a woman who has lost her breast to cancer surgery.

2 Tattoo ink isn't actually ink. It comprises pigments that are suspended in a carrier solution.

3 On which part of the body is it most painful to get a tattoo? The answer depends on your pain threshold and, it seems, whether you're a doctor or tattoo artist. While tattoo artists unanimously vote the ribcage as pain central, doctors say it is sensitive areas of the body where there are clusters of pain sensors. Dr Derrick Aw, consultant dermatologist at the Department of Medicine in National University Hospital, pointed out areas where there are high concentrations of nerve endings like the palm of your hand or the sole of your foot, areas where there is little fat tissue and bone beneath like the forehead or shin and sensitive areas like genitalia.

4 Out, damned spot, out I say, so said Lady Macbeth. You may utter the same if you're trying to remove your green dragon tattoo. Dr Yeap Choong Lieng, consultant plastic and cosmetic surgeon at Yeap Plastic Reconstructive and Cosmetic Surgery, said: 'The easiest to remove is the black pigment followed by the red. The green pigment is the hardest to remove, requiring many sessions (of laser treatment) and the skin will often scar in the process.'

5 According to Guinness World Records, the world's most tattooed person is New Zealand-born performer Lucky Diamond Rich, who has his entire body covered with black ink.

This story was first published in Mind Your Body, The Straits Times, on May 7, 2008.