It was the question that gripped the nation Tyga’s Instagram followers and started an internet frenzy. On Jan. 11, the rapper, 27, posted a saucy photo of his bikini-clad girlfriend, Kylie Jenner, sitting on his lap — but all anyone could talk about was the mysterious-looking bump on her leg. “Is that a wart on top of her right knee?” asked one fan, while another suggested it was a ladybug. Other theories: It’s part of a scar Kylie, 19, has had since childhood (it’s definitely not) and — our favorite — the youngest member of the Kardashian-Jenner clan has a third nipple in a most unfortunate place (not that there’s a fortunate place for those). At left, see our wild guesses about what random things could have gotten stuck to…