Goody two shoes
From Tardis Wiki, the free Doctor Who reference
Missy claiming that, when the Doctor left the Academy, he went "all goody-two-shoes". (WC: Who is the Master?)
Missy, during her own index file, explained that, after the Doctor left the Academy, he became a "goody-two-shoes", while she became "bananas", going "out to party" by spreading chaos and destruction. (WC: Who Is The Master?)
