Green’s Dictionary of Slang

1. (US) Paris [Fr. cliché ooh-la-la].

1925

L.A. Times 11 Jan. VI2/1: [heading] Miniature Motor Cars Developed by French Engineers Amaze American Government ‘Paris Flivver’ is Tiny Affair; Commerce Department Motor Head Home Again; Describes One-Man Taxis in ‘La-La Land’.

2. (orig. US) Los Angeles; also attrib [L.A. n. but note la-la land n.].

1984		Palm Beach Dly News (FL) 8 Dec. n.p.: The sterile state-of-the-art mentality of the Beverley Hills police force and the [...] unreal foreign-planet-ozone layer of La-La Land culture.
1986		R. Campbell In La-La Land We Trust (1999) 10: I want to read fairy tales about [...] corpses rising up from graves all over La-La Land.
1999		Guardian Guide 9–15 Oct. 8: Now that she’s on the loose in La-La-Land, will she once again put the ‘ho’ back in Hollywood.
2000		Guardian Weekend 9 Dec. 3: Well bleached by the bright brazen sun of La-La Land.