In S1E12, after Lane and Rory get in trouble for lying to their mothers about their evening activities, Rory climbs a tree to knock on Lane’s bedroom window. When Lane opens the window, Rory says, “What’s up, Rapunzel?”
Rapunzel is a German fairy tale about a girl who is trapped in a high tower by an evil witch. She meets a prince and eventually (after haircuts and blinding thorns and babies) marries him and lives happily ever after. See Into the Woods for a more gruesome version or Tangled for the adorable version.