What That Mean?

Hello, now I will tell you about something, not tell, but I have one question you must answer now! #maksa especially VIP. What that mean : BOOM SAKALAKA? It's magic? or just regular words? BOOM SAKALAKA in BigBang's sang, FANTASTIC BABY. And what's that? in Seungri or Taeyang head. a words, but I don't know his write. Please tell me about that. Daebak BIGBANG! ^^