This is so freakin’ adorable! Kylie Jenner, 18, has been a total Gwen Stefani, 46, fangirl since she was just a little kid, and on Mar. 29 she proved it with a precious throwback video. Turns out, the youngest member of the Kardashian Klan was randomly pulled onstage during a show, and the pair had a super cute duet together.