The sound of a shotgun explosion. The word originated in 80's gang culture but first appeared in popular media when the LA rap group Boo-Yaa T.R.I.B.E. issued their debut single “Coming Hard to America” in 1988 followed by their first album New Funky Nation in 1990. However, the term didn’t begin to receive universal popularity until fellow LA rappers Cypress Hill released their debut album Cypress Hill in 1991, which used the term “Boo-yaa” liberally and sold more than two million copies on its way to becoming one of hip-hop’s classic albums. Later, the term would become known as a general shout of exuberance.
Lettin' out a bullet, this is going boo-yaa,
you're stuck in my hood, so what ya gonna do now?
-Cypress Hill, "Hand on the Pump" (1991)
Boo-yaa! That stock is a definite buy!
Jim Cramer, Host of "Mad Money" on CNBC (2006)