P. J. Clarke's is a famous saloon, established 1884 and occupying a building located at 915 Third Avenue on the northeast corner of 55th Street in New York City.
P.J. Clarke's was used to represent Nat's Bar in the 1945 Ray Milland movie The Lost Weekend, directed by Billy Wilder. Charles R. Jackson, author of the novel on which that movie was based, was a regular at P. J. Clarke's.
Johnny Mercer penned "One for My Baby (and One More for the Road)" on a napkin while sitting at the bar at P.J. Clarke's (The bartender at that time was named Tommy Joyce, and Mercer reportedly apologized to Joyce, saying "I couldn't get your name to rhyme".)Read article at Wikipedia