Katy Perry: Halloween Cat Mask!

Katy Perry rocks a cat mask in honor of Halloween as she steps out of the M.E.N. Arena on Monday (October 31) in London, England.

The 27-year-old singer performed a concert that evening, and apparently surprised her fans by coming out in a Rihanna mask! “Ya girl,” she said via Twitter when a fan asked if she really did.

PHOTOS: Check out the latest pics of Katy Perry

“Nothing like a night of watching The Shining in your hotel room to give you a good nights sleep! #REDRUM” Katy tweeted about her spooky Halloween evening!

FYI: Katy is wearing a chic Valentino cashmere coat.