"RATATATA" lyrics : what do I hear ??

Hi everyone!

I need help, 'cause I'm getting crazy about the first chorus of Electric Callboys x BABYMETAL's 'RATATATA'.
I'm creating that song to play it with my wife on UltraStar (Karaoke game).
I have to put the lyrics right now. But I have a little problem with what I'm hearing ;
At 0:50, I can swear I'm hearing
"Bun-bun-bun
Moving, bun-gi-bun-bun-bun-bun"

I can't find anything on internet about that. I first thought it was a japanese way to pronounce "bun", like they sometimes use "ru" when using occidental words. But the other "bun" are pronounce correctly and without "gi".

What do you think ?