India, March 29 -- S inger Katy Perry and former Canadian Prime Minister Justin Trudeau shared a playful moment from their recent outing on social media. On Friday, the 41-year-old singer posted a glimpse of their date night on Instagram, joking about her 13-year age gap with Trudeau, who is 54. "How old would you be if you didn't know how old you were?" she wrote. The post showed the two trying a viral age-guessing filter, which estimated Perry to be 33 and Trudeau 43, both younger than their actual ages. HTC...