Also known as " blowing a raspberry" or "a raspberry". It is made by placing the tongue between the lips, or alternately placing the lips against any area of skin, and blowing. It is meant to replicate a fart and is a sign of derision. The term "Bronx cheer" dates back to the 1920s to signify this sound. The other definitions are historically incorrect if they do not mention this sound.
by Bronx old timer August 16, 2020