Yeah I was wondering about that, because I never thought of "boo" as a word really. I assumed it transcended language barriers, so I was curious if this even made any sense. If not, what's the Spanish equivalent of boo?

It's "boo!" but the "b" sound is lighter in Spanish, so it sounds more like "bUoo!" What I want to know is do Spanish speakers know whoBruce Springsteen is?

Cool. I was thinking it was kind of like the sound a Rooster makes (in America it's cockadoodledo and in Spanish it's kikirikí, two entirely different human language interpretations on a non-human sound), but listening again I did hear a bit of a "B" when they start yelling. I guess like most words its origins are Latin (http://www.etymonline.com/index.php?term=boo) and was mostly popular in England, so I guess I was half-right, but was also used to Italy and most likely Spain around the same time. :)