up to one's tricks up to one's old tricks
or up to one's old tricks
phraseIf you say that someone is up to their tricks or up to their old tricks, you disapprove of them because they are behaving in the dishonest or deceitful way in which they typically behave.
[informal, disapproval] I have no respect for my father who, having remarried, is still up to his old tricks.
See full dictionary entry for trick