Paul Muni's performance as Tony Camonte in Howard Hawks' classic gangster movie Scarface (1932) generated a number of complaints from the real mafia about the unflattering portrayal of organized crime. Shortly after the film's release, Muni boarded the S.S. Pennsylvania (headed for California via the Panama Canal) and discovered that Bugsy Siegel, a notorious West Coast gangster, was also on board. Siegel certainly made his presence known, walking the deck every day with his bodyguard and glaring at Muni at every opportunity.
One evening, Muni found himself cornered by one of Siegel's bodyguards in the dining room. "Bugsy and us went to that Strand Theater to see that new picture," he grunted. "Hey, that-there was no actor. He was the real goods. Tell me, Mister, what mob was you with?" Muni's reply? "The Schwartz mob -- Lower East Side."
[Muni was in fact a New York Jew -- born Meshilem Meier Weisenfreund.]