the whiskers they come from within
A saying any Phangirl or Phanboy would know. It comes from when two YouTubers, Danisnotonfire (aka Daniel Howell), and AmazingPhil (aka Phil Lester) made a collab Q/A where they draw cat whiskers on their faces with black marker. This series, only happening once a year, is named Philisnotonfire, as a mix of their internet names at the time. This phrase was coined up by them or some fans. "The whiskers, they come from within" is even on a few items of merch that they sell.
Girl while watching a Philisnotonfire video: Oh my God the whiskers they come from within! (She feels the whiskers in herself)