5 / 13

Pharrell Williams

MIAMI BEACH, FL - DECEMBER 07: Producer Pharrell Williams attends a private dinner celebrating Remo Ruffini and Moncler's 60th Anniversary during Art Basel Miami Beach on December 7, 2012 in Miami Beach, Florida. (Photo by Dimitrios Kambouris/Getty Images for Moncler)

What Were They Thinking?!

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