Taylor Swift is very protective of her belly button. This is common knowledge.
"When you start showing your belly button then you're really committing to the midriff thing," she once explained to Lucky. "I only partially commit to the midriff thing."
Choosing to edit in some rock-hard abs, or Steve Buscemi's face, or a weirdly high amount of penises for the ratio of dudes working on this challenge, the speculation of what Tay could be hiding underneath her high-waisted skirts varied from the weird, to the hilarious, to the downright NSFW.
In short: the internet is amazing, and even when Taylor DOES show off the Tayvel (you're welcome), we're never going to be 100% sure if it's real.