Green’s Dictionary of Slang

(US) something or someone outstanding in some way, whether good, stylish or pleasing, or occas. with negative connotations.

1881		Dly L.A. Herald 13 Aug. 2/3: He calls a beautiful woman a ‘lalla’.
1886		Nat. Police Gaz. (NY) 25 Sept. 14/1: Connor’s hit over the right field fence was a lalah.
1890		Arizona Republic (Phoenix, AZ) 7 Sept. 2/3: The door opened and in entered the finest specimen of a colored dude I ever laid my eyes upon. He was a la la.
1896		W.C. Gore Student Sl. in Cohen (1997) 3: la la n. A delightful, charming person. Often used ironically. Lu lu n. Same as la la.
1902		Ade Forty Modern Fables 66: He must be a Lah-Lah if he can hold to that Gait. I suppose he plays the Drunken Sailor with his money.
1913		E.L. Warnock ‘Terms of Approbation And Eulogy’ in DN IV:i 17: la-la. A swell, a stylish person [...] ‘That lady is a la-la’.
1916		J. Lait ‘Charlie the Wolf’ in Beef, Iron and Wine (1917) 37: ‘It’s nice?’ she asked. ‘It’s a lallah,’ said the Wolf.
1999		Guardian G2 7 Oct. 22: Ally is a work-place version of Bewitched, the loony housewife replaced by a la-la lawyer.