“I did 'We Can't Stop' for Rihanna, but it never worked. Every time I would play 'We Can't Stop' I was like 'this is the new 'Party in the U.S.A.'' I was like OK if I keep saying this is the new 'Party in the U.S.A.,' why don't I go to the girl who did 'Party in the U.S.A.?'”