Singer Billie Eilish has shown off one of her tattoos that she said her fans would never see. A rare bikini snap posted on Instagram by one of Billie's friends has shown off her chest ink. Annabel Zimmer posted the photo of the Bad Guy singer wearing a Miaou bikini top with the tattoo visible.The 21 year old was enjoying the sun as she lounged around with a pair of Versace sunglasses covering her eyes.