Definition from Wiktionary, the free dictionary
- (slang) An exclamation of joy, excitement or triumph.
- 1996 Jerry Maguire (film) -- Catch the ball!' BOO YA! Touchdown! I make miracles happen! 
- 1997 Jackie Brown (film) -- As Jackie Brown (Pam Grier) is sitting in the fitting room and sliding the bag filled with bath towels, books and money under the dressing room door to Melanie (Bridget Fonda), Jackie adds an extra wad of cash - a "cherry on top..." and exclaims, "Boo-ya!"
- 2002 Scooter and the Galactic Starship by Douglas R. Robinson -- "Boo-ya!" yelled Jay as he sank an outside shot from the edge of the lawn. "Nothing but net. Just wait till next week, I'm going to light it up for a whole bunch of points." 
- 2002 Geoffrey Litwack 2002 Annual by Geoffrey Litwack -- [I should] try to get an American Express Stanwood card. That way I can get free upgrades. Boo-ya! Not to Iowa, though. Out of the country.