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Katy Perry

NEW YORK, NY - NOVEMBER 27: Katy Perry attends the Unicef SnowFlake Ball at Cipriani 42nd Street on November 27, 2012 in New York City. (Photo by Stephen Lovekin/Getty Images)

What Were They Thinking?!

This week's worst-dressed crew includes Kristen Stewart, Kanye West, and Katy Perry. -- By Matt Whitfield, Yahoo! Staff