From the OED Online:
lallapaloosa
U.S. slang
[Fanciful formation.]
Something outstandingly good of its kind.
1904 H. MCHUGH I'm from Missouri vi. 89 Saturday night we had our final
parade with the fireworks finish, and it was a lallapalootza! 1909 F. B.
CALHOUN Miss Minerva xxvi. 204 You sho' is genoowine corn-fed, sterlin'
silver, all-wool-an'-a-yard-wide, pure-leaf, Green-River Lollapaloosas.
1911 Dialect Notes III. 545 A second word~list from Nebraska...
Lallapaloosa, something fine or grand; a term of approbation. You have a
lallapaloosa of a hat, That's a lallapaloosa. 1926 WODEHOUSE Heart of Goof
i. 40 To-day he had been so preoccupied with his broken heart that he had
made his shots absently, almost carelessly, with the result that at least
one in every three had been a lallapaloosa. 1933 A. MERRITT Burn Witch
Burn! (1934) x. 135 She thinks this doll woman a lallapaloozer. Yeah, a
lallapaloozer, a corker! 1947 W. STEVENS Let. 28 Feb. (1967) 547, I think
that the book, as a book, is a lollapalooza. 1951 New Yorker 20 Oct. 28/3
Though I had long ago forgotten the background, characters, and plot, I
distinctly remembered it as a lollapaloosa. 1966 Listener 2 June 811/1
What is the tone of lalapalooza, since Hector was a pup, bumbershoot,
hornswoggle, Milwaukee tumour, benzine buggyor lalapalooza's equivalent,
poustouflante? 1970 S. J. PERELMAN Baby, it's Cold Inside 172 All agreed
that Luba Pneumati was a lollapaloosa, the Eighth Wonder of the World.