Green’s Dictionary of Slang

(W.I./UK black teen) an excl. of delight, pleasure, made by using the mouth to simulate gun shots fired in celebration or appreciation of something.

1992		M. Beat [song title] Booyaka.
1997		Jimmy B. ‘Jika Jika’ 🎵 Booyaka! Booyaka! Keep it booming.
1999		Observer Screen 15 Aug. 7: Ali G [...] Trademark: ‘Wicked!’ ‘Boo-yakka!’.
2001		(con. 1981) A. Wheatle East of Acre Lane 246: He trained his aim on a nearby tree and imagined it to be a policeman. ‘Booyaka!’ he cried.