Katy Perry needed 17 stitches after a mysterious injury in Toronto over the weekend. On Sunday, she performed at the MuchMusic Awards, but somehow got hurt dancing at a local club. She posted yesterday on Twitter, “17 stitches later . . . Don’t make fun of my dance moves tomorrow. That’s what got me here in the 1st place! Thanks for the souvenir, Canada)!” Perry didn’t say where or how she got hurt. Her rep didn’t respond by press time.