LORELAI: Do you think [Luke’s] dated anyone since Rachel?
RORY: I don’t know. Where would he meet anyone? He’s either here or in his apartment.
LORELAI: Maybe he has a secret life. Maybe he’s got a little chippy stowed away in Mount Pilot.
Mount Pilot is a fictional town in the sitcom, The Andy Griffith Show (1960-68). The show is set in the fictional town of Mayberry, North Carolina, and Mount Pilot is a neighbouring larger town. Mayberry is apparently based on the real town of Pilot Mountain in North Carolina, with its name inspiring Mount Pilot. (There is a real Mayberry in Virginia, about 22 miles from Pilot Mountain).
The archetypal small town of Mayberry was almost named Taylortown and had a sheriff named Taylor [!!!!!], and like Stars Hollow, only had one traffic light and a cast of lovable eccentric characters. Like Stars Hollow, it was about thirty miles from the state capital, and had a population of ambiguous size.
The name Mayberry is used in popular culture as a term to refer to idyllic small town life and rural simplicity. Lorelai is humorously using the name “Mount Pilot” to mean any real life neighbouring town to the “Mayberry” of Stars Hollow.
“Chippy” is dated American slang for a prostitute or promiscuous woman; it goes back to the late 19th century and is of obscure origin.