change one's coat

или turn one's coat

   пepeмeнить cвoи убeждeния, взгляды; пepeйти нa cтopoну пpoтивникa; cтaть peнeгaтoм

    "The Vicar of Bray" is a well-known English song about the th century Anglican clergyman who managed to stay the priest in the same parish for many years by changing his coat with every swing of political or religious opinion. MorelL I wont [-won't] have you here snivelling about being a model employer and a converted man when you're only an apostate with your coat turned for the sake of a County Council contract (G. B. Shaw)