Rory warns her mother not to refer to Chicago as “Chi-Town” when she meets her new boyfriend Dean, who is from Chicago.
The term Chi-Town originated as trucker’s slang to refer to Chicago via citizens’ band radio; it obviously takes the first three letters of Chicago and adds Town to it. The slang term spread more widely than CB radio usage after it featured in the 1975 novelty song Convoy by C.W. McCall, from the album Black Bear Road. The song went to #1 in the national charts, as well as #1 in the country charts, and inspired the 1978 film Convoy.
The Annotated Gilmore Girls 