Jim Dyson/Getty Images Just days after pictures emerged of Katy Perry packing on the PDA with Justin Trudeau, the singer had a very interesting response to a fan's proposal while performing in London. The "California Gurls" singer brought her Lifetimes Tour to The O2 arena on Monday, October 13, and was surprised by an eager fan named Darren, who proposed to her after being invited onstage. "I heard you're single," Darren said per footage posted on TikTok. "You heard I'm single? That's interesting," Perry, 40, responded.