Hello All.  After further research and asking some "old  folks," I do believe 
the "G" means Gramercy Park, because several older NYer's  have told me that 
it was still a term when they were young.     "Up in G."      I was told by a 
92 year old woman that  "not only was the rich and famous up in G, but they 
had fancy fences around the  gardens and Parks to keep the poor folks out."   
Originally  meaning Gramercy Park and referring to the "hoytie toytie's" who 
became more  sophisticated and moved uptown to "Gramercy Park,"  it became a 
phrase for  anyone who moved "up and out of the neighborhood"  and sometimes 
meaning  "they think they're too good for us."   I am currently researching and  
writing a book about Old Manhattan and I truly appreciate this type of  
discussion, very colorful and thought provoking.  I would appreciate any  one else who 
would mention old "sayings" "Colloquialism's" and "slang words"  used 
exclusively in NEW YORK.  Thanks.