The etymology of boo is uncertain. The OED compares it with the Latin boare or the Greek βοᾶν, meaning to "cry aloud, roar, [or] shout." Older dictionaries suggest it could be an onomatopoeia ...

Not long ago, Fred Armisen was reminiscing about the sound-effect LPs he used to stock at the Chicago record store where he worked in the Nineties. These vinyl platters contained all kinds of sounds, ...