賣乖

to show off one's cleverness / (of sb who has received beneficial treatment) to profess to have been hard done by

to sell / to betray / to spare no effort / to show off or flaunt

(of a child) obedient, well-behaved / clever / shrewd / alert / perverse / contrary to reason / irregular / abnormal

to behave ingratiatingly

to have benefited from sth but pretend otherwise / to claim to be hard done by, even though one has benefited

to curry favor by showing obeisance (idiom)