Buffy The Vampire Slayer S4 Ep 15 - F2F Body Swap

Season 4 Episode 15 This Year's Girl
As the fight between Buffy and Faith gets more intense, the police arrive. Faith puts the gift from the Mayor on her hand and grabs Buffy's hand. Light flows through them and after a few seconds of the two looking at each other in confusion, Buffy punches Faith and knocks her out, leaving her to be arrested. Buffy then smashes the metal contraption from the Mayor and when Joyce asks Buffy if she's okay, she responds: "Five by five.