I think I understood it as "beetle bomb" or "feetlebomb" when I was a kid. I don't believe I ever heard the Spike Jones performance of William Tell Overture when I was a kid, but other kids would yell out "the winner feetlebom" at the end of races, and that's how I learned the term. I don't think I heard the recording until we discussed it in another thread at Mudcat (linked above).

Many lyrics sites list the winner as feitlebaum.

Wikipedia says the "humorous horse race calls (were)performed by Doodles Weaver in the style of the famous announcer Clem McCarthy." Wikipedia says further:

Perennially trailing the field with distant 20-to-1 odds is the horse Feetlebaum (one of Weaver's radio-show characters was Professor Feetlebaum). The horse's name is always spoken in a deep, two-note "foghorn" cadence. During the race, Feetlebaum keeps falling farther and farther behind the field.
As the race nears its finish, the announcer goes on a tangent, impersonating broadcaster Clem McCarthy, who had called the famous Seabiscuit-War Admiral match race in 1938 and also the famous Joe Louis-Max Schmeling boxing rematch of the same year. In this case, Weaver's now gravelly-voiced track announcer begins describing a boxing match.
The song concludes with Weaver announcing the winner... Feetlebaum!

I think we can say with certainty that there is no agreement on the spelling of the name of the horse that won this imaginary race. For the first half-century of my life, I had no idea the name came from a Spike Jones recording. I thought it came from some kids I knew in second grade in Detroit.

-Joe Offer-