You'll Never Guess the HUGE Pop Star Hiding Under a Bunny Mask, Suspenders, and Crazy Stuffed-Animal Pants!

This photo stirs up so many feelings: terror, curiosity, a weird desire to watch Donnie Darko.

It also raises a big question:

The pop star hiding under this avant-garde ensemble is one of the biggest and best-selling artists of all time, but who is she?

Here's a hint: What happens in Vegas, stays in Vegas.

Click through to find out!