Green’s Dictionary of Slang

something or someone extraordinary or wonderful.

1888		E.L. Dorsey Midshipman Bob 93: ‘Fore-top-gallant studdingsail-boom-tricing-line-block strap-thimble.’ Ain’t that a whizzer? [OED].
1914		Ade ‘The New Fable of the Lonesome Camp’ in Ade’s Fables 257: Elam was the main Whizzer in a huddle of Queen Annes, bounded on the North by a gleaming Cemetery [...] Claudine was the other two-thirds of the Specialty.
1928		T. Thursday ‘Sock of Ages’ in Fight Stories Oct. 🌐 But the tenth and final frame was a whizzer!
1947		F. Brown Fabulous Clipjoint (1949) 144: I think he’s holding something back, but I don’t know what it is. In fact, I wouldn’t be surprised, Ed, if he’s running a ring-tailed whizzer on us. But I can’t figure where.
1950		R. Starnes And When She Was Bad She Was Murdered 186: I have just throwed together a whiz-dinger of a shrimp creole.
1963		(con. 1944) L. Glassop Rats in New Guinea 87: You might have been the Wizard of Nerridale, but I was the Whizzer of Nerridale.
1975		L. Rosten Dear ‘Herm’ 31: Our son Alvin and ‘Penny’ (our oldest daughter) are real whizzers in Geog.