SAIL UNDER FALSE COLORS

{v. phr.} 1. To sail a ship, often pirate, under the flag of another country. * /The pirate ship flew the American flag until it got near, then raised the black flag./ 1. To pretend to be what you are not; masquerade. * /The garage hired Jones as a mechanic, but fired him when they found he was sailing under false colors./ * /They found out that Smith was an escaped convict who had been sailing under false colors as a lawyer./