Originally a Japanese incantation--usually recited twice--to avoid being struck by lightening. Strictly speaking, it is chanted to ward off bad luck much like "knock on wood", but in common usage today, it is chanted simply to ward off any unlucky situation.
In the song "Kuwabara Kuwabara" by Dreams Come True, a girl is unexpectedly going to be visited by her parents and she hurries to get rid of all signs of the guy she is living with. (trans.)
"KUWABARA KUWABARA, I chant the spell
and erase the heavy thoughts from my mind
KUWABARA KUWABARA, I sweep away
his big shoes along with my cold sweat... Safe!"