"You Know What You Did" is the first episode of the third season of "The Hills". It originally aired on MTV on August 13, 2007. In the episode, Lauren Conrad ends her friendship with former housemate Heidi Montag after suspecting that Heidi and her boyfriend Spencer Pratt fabricated rumors of a sex tape involving Lauren and her ex-boyfriend Jason Wahler. The ensuing feud between the women becomes a central focus of the series, and is carried through each subsequent season in which Conrad appears.