Blowing a raspberry comes from the Cockney rhyming slang "raspberry tart," fart. Rhyming slang was particularly used in British comedy to refer to things which would be unacceptable to a polite audience, particularly on the BBC.
One of the most famous uses of the Bronx cheer is in the song "Der Fuehrer's Face" (from the Disney animated film of the same name), as recorded by musical comedian Spike Jones in 1942, which shows disdain for Adolf Hitler with the repeated refrain "We Heil! (Bronx cheer) Heil! (Bronx cheer) Right in Der Fuehrer's Face!"
