18 - Spiking the Punch at the School Reunion (S2, Ep3)

We watch "School Reunion" (Series 2, Episode 3) where the Scooby Gang embodied by the Doctor, Rose, Mickey, Rose's future self (Sarah Jane Smith!), and Mickey's future self (K-9!) investigate mysterious goings on at school. Whilst there, Rose starts a cat fight, Mickey crashes the party, and the Doctor gets his dog fixed.